Newsgroups: comp.infosystems.www.providers
From: hoey@aic.nrl.navy.mil (Dan Hoey)
Date: 02 Jan 1995 19:41:00 GMT
Subject: Re: Secure HTTPD (NCSA and CERN) question
raha...@cc.umanitoba.ca (Budi Rahardjo) writes:
> We would like to allow our users to create their own public_html
> directories, but we don't want them to create symbolic links
> to anywhere outside their public_html.
...
> If I don't put "SymlinksIfOwnerMatch" (and also don't have FollowSymlink),
> their "public_html" directories (in their home directories) are not
> accessible. Maybe that's because their home directories are on a
> different fileserver?
I had exactly that problem. My solution was the patch I enclose
below. I mailed this to the HTTPD developers and posted it to
c.i.w.p. And I haven't heard a word about it since. I would most
certainly like to know if there's anything wrong with it.
Dan Hoey
Hoey@AIC.NLR.Navy.Mil
================================================================
From: hoey@aic.nrl.navy.mil (Dan Hoey)
Newsgroups: comp.infosystems.www.providers
Subject: HTTPD 1.3 patch for automount symlinks
Date: 21 Dec 1994 00:27:51 GMT
Organization: Navy Center for Artificial Intelligence
I sent this to the httpd developers and got the automated "we're too
busy to read your message" message. I'd appreciate any comments.
I had a problem installing NCSA/1.3 httpd for Unix. It led me to
patch my copy of the source code. I don't believe I am alone, or even
rare, in having this problem, so you may want to install something
similar in later versions.
Users on this system have directories on automounted partitions, and
to get to an automounted partition you have to follow a symlink.
I was not willing to enable FollowSymLinks, because users will put
links to places without thinking of where they are going.
SymLinksIfOwnerMatch had the problems that
1. I am concerned that some setuid programs might not mind creating
symlinks owned by a privileged user. The ownership of a
symlink is not designed to have any effect on the
accessibility of the thing linked to.
2. It did not solve the problem, because some of the automounted
partitions might not be owned by the owner of the link.
I considered making httpd not check the ownership of links traversed
to get to users' home directories, but that seemed to require more
modification to the link-checking code than I was willing to perform.
I decided to solve the problem by adding the "AutomountPoint"
directive to httpd. AutomountPoint specifies a directory that is
maintained as a logical mirror of the system name space. Specifying
AutomountPoint /tmp_mnt
enables httpd to follow links of the form
/p1/p2/.../pn -> /tmp_mnt/p1/p2/.../pn
even if following symbolic links is usually disabled.
I consider this relatively secure, since the ownership of /tmp_mnt
prevents adding any file /tmp_mnt/p1/p2/.../pn that shouldn't normally
accessible as /p1/p2/.../pn. I am somewhat concerned that some
circumvention of this may be possible by the use of race conditions,
but I think using such a race condition would require the intentional
collusion of a local user, which I am not so concerned about--that
user would be able to simply copy materials into the public_html
directory, anyway.
Here are context diffs of the files I changed. I hope you find this
useful.
Dan Hoey
Hoey@AIC.NRL.Navy.Mil
WWW page
===================================================================
RCS file: RCS/httpd.h,v
retrieving revision 1.1
diff -c5 -r1.1 httpd.h
*** /tmp/RCSAa10124 Tue Dec 20 17:41:23 1994
--- httpd.h Mon Dec 12 17:39:37 1994
***************
*** 234,243 ****
--- 234,246 ----
#define RESOURCE_CONFIG_FILE "conf/srm.conf"
/* The name of the MIME types file */
#define TYPES_CONFIG_FILE "conf/mime.types"
+ /* The name of the NFS automount point */
+ #define AUTOMOUNT_POINT ""
+
/* The name of the access file */
#define ACCESS_CONFIG_FILE "conf/access.conf"
/* Whether we should enable rfc931 identity checking */
#define DEFAULT_RFC931 0
***************
*** 401,410 ****
--- 404,414 ----
extern char *server_hostname;
extern char server_confname[MAX_STRING_LEN];
extern char srm_confname[MAX_STRING_LEN];
extern char access_confname[MAX_STRING_LEN];
extern char types_confname[MAX_STRING_LEN];
+ extern char automount_point[MAX_STRING_LEN];
extern int timeout;
extern int do_rfc931;
#ifdef PEM_AUTH
extern char auth_pem_decrypt[MAX_STRING_LEN];
extern char auth_pem_encrypt[MAX_STRING_LEN];
===================================================================
RCS file: RCS/http_config.c,v
retrieving revision 1.1
diff -c5 -r1.1 http_config.c
*** /tmp/RCSAa10127 Tue Dec 20 17:41:56 1994
--- http_config.c Mon Dec 12 17:39:08 1994
***************
*** 22,31 ****
--- 22,32 ----
char *server_hostname;
char srm_confname[MAX_STRING_LEN];
char server_confname[MAX_STRING_LEN];
char access_confname[MAX_STRING_LEN];
char types_confname[MAX_STRING_LEN];
+ char automount_point[MAX_STRING_LEN];
int timeout;
int do_rfc931;
#ifdef PEM_AUTH
char auth_pem_decrypt[MAX_STRING_LEN];
char auth_pem_encrypt[MAX_STRING_LEN];
***************
*** 52,61 ****
--- 53,63 ----
server_hostname = NULL;
make_full_path(server_root,RESOURCE_CONFIG_FILE,srm_confname);
/* server_confname set in httpd.c */
make_full_path(server_root,ACCESS_CONFIG_FILE,access_confname);
make_full_path(server_root,TYPES_CONFIG_FILE,types_confname);
+ strcpy(automount_point,AUTOMOUNT_POINT);
timeout = DEFAULT_TIMEOUT;
do_rfc931 = DEFAULT_RFC931;
#ifdef PEM_AUTH
auth_pem_encrypt[0] = '\0';
***************
*** 159,168 ****
--- 161,174 ----
cfg_getword(w,l);
if(w[0] != '/')
make_full_path(server_root,w,types_confname);
else strcpy(types_confname,w);
}
+ else if(!strcasecmp(w,"AutomountPoint")) {
+ cfg_getword(w,l);
+ strcpy(automount_point,w);
+ }
else if(!strcasecmp(w,"Timeout"))
timeout = atoi(l);
else if(!strcasecmp(w,"IdentityCheck")) {
cfg_getword(w,l);
if(!strcasecmp(w,"on"))
===================================================================
RCS file: RCS/http_access.c,v
retrieving revision 1.1
diff -c5 -r1.1 http_access.c
*** /tmp/RCSAa10121 Tue Dec 20 17:40:50 1994
--- http_access.c Mon Dec 12 17:39:21 1994
***************
*** 139,149 ****
if((!(opts[x] & OPT_SYM_LINKS)) || (opts[x] & OPT_SYM_OWNER)) {
struct stat lfi,fi;
lstat(d,&lfi);
if(!(S_ISDIR(lfi.st_mode))) {
! if(opts[x] & OPT_SYM_OWNER) {
char realpath[512];
int bsz;
if((bsz = readlink(d,realpath,256)) == -1)
goto bong;
--- 139,149 ----
if((!(opts[x] & OPT_SYM_LINKS)) || (opts[x] & OPT_SYM_OWNER)) {
struct stat lfi,fi;
lstat(d,&lfi);
if(!(S_ISDIR(lfi.st_mode))) {
! if(opts[x] & OPT_SYM_OWNER || *automount_point) {
char realpath[512];
int bsz;
if((bsz = readlink(d,realpath,256)) == -1)
goto bong;
***************
*** 153,165 ****
strcpy(t,"../");
strcpy(&t[3],realpath);
make_full_path(d,t,realpath);
getparents(realpath);
}
! lstat(realpath,&fi);
! if(fi.st_uid != lfi.st_uid)
! goto bong;
}
else {
bong:
sprintf(errstr,"httpd: will not follow link %s",d);
log_error(errstr);
--- 153,170 ----
strcpy(t,"../");
strcpy(&t[3],realpath);
make_full_path(d,t,realpath);
getparents(realpath);
}
!
if(strncmp(realpath,automount_point,strlen(automount_point))
! ||
strcmp(realpath+strlen(automount_point),d)) {
! if(!(opts[x] & OPT_SYM_OWNER))
! goto bong;
! lstat(realpath,&fi);
! if(fi.st_uid != lfi.st_uid)
! goto bong;
! }
}
else {
bong:
sprintf(errstr,"httpd: will not follow link %s",d);
log_error(errstr);
================================================================
---
Newsgroups: sci.math
From: hoey@aic.nrl.navy.mil (Dan Hoey)
Date: 04 Jan 1995 01:06:05 GMT
Subject: Re: 1995 a very interesting number
Reiner.Eu...@psychol.uni-giessen.de (Reiner Euler) writes:
> >> Which 4-digit year "abcd" solves the conditions
> >> ab|cd|abcd (condition A)
> >> abc|bcd (condition B) ?
barring a==b==c==d. As I noted (modulo a careless, but minor,
mistake, that Reiner corrected, modulo a careless, but minor mistake,
that I've corrected):
> >Reiner notes that all the numbers are very close to 10000/n, for
> >n=8,6,5,2....
> >This is mostly because of condition B.
> > If k(abc) = (bcd),
> > then k(abcd) = 10(bcd) + k d
> > then (10-k)(abcd) = 10000a - k d
> > then (abcd) = 10000/((10-k)/a) - (k d)/(10-k).
The question then boils down to showing that (10-k)/a is an integer.
It isn't implied by condition B alone (e.g. (abcd)=3748) but is true
by inspection on both conditions.
Generalizing to other bases, I have discovered that in base 25,
3I | IF | 3IIF, 3II | IIF, but 10000/3IIF is approximately K/3 (or
20/3 decimal), not an integer.
Generalizing to longer numbers, I have discovered that in base 7,
2541 | 2541 | 25412541, 2541254 | 5412541, but 100000000/25412541 is
approximately 5/2, not an integer.
This is perhaps trivial, since both halves of the number are the same,
but in base 12, 37249 | 72496 | 3724972496, 372497249 | 724972496, but
10000000000/3724972496 is approximately A/3 (or 10/3 decimal), not an
integer.
It appears that for more than four digits, the only decimal numbers
satisfying the analogues of the conditions are 166...664, 199...995,
and 499...998, but I have not proven this.
Dan
Hoey@AIC.NRL.Navy.Mil
---
Newsgroups: sci.math
From: hoey@aic.nrl.navy.mil (Dan Hoey)
Date: 04 Jan 1995 01:46:48 GMT
Subject: Re: Number theory question
geoff...@oracorp.com (Geoffrey Hird) writes:
> I have been told that the following is an open problem in number
> theory.
> Do there exist powers 2^n and 3^m such that |2^n - 3^m| = 1,
> other than the two cases 2,3 and 8,9 ?
This is a case of Catalan's conjecture. R.K.Guy, in _Unsolved
Problems in Number Theory, 2nd Edition_ (Springer-Verlag, 1994, ISBN
0-387-94289-0), p.155, says:
Except that there remains a finite amount of computation, Tijdeman
has settled the old conjecture of Catalan, that the only
consecutive powers, higher than the first, are 2^3 and 3^2. But
this finite amount of computation is far beyond computer range and
will not be achieved without some additional theoretical ideas.
Langevin has deduced from Tijdeman's proof that if n,n+1 are
powers, then n < exp exp exp exp 730 ....
There is nothing in the article to suggest that the problem is easier
if restricted to powers of two and three, and some of the results rely
both bases being greater than two. Guy cites R. Tijdeman, On the
equation of Catalan, _Acta Arith_, 29(1976) 197-209; MR 53 #7941.
Dan Hoey
Hoey@AIC.NRL.Navy.Mil
---
Newsgroups: alt.college.fraternities, talk.bizarre, alt.conspiracy
Followup-To: talk.bizarre
From: hoey@aic.nrl.navy.mil (Dan Hoey)
Date: 04 Jan 1995 02:45:17 GMT
Subject: Re: What is a fraternity ?
parry@geo.ucalgary.ca goes:
( the aliens caused gt50...@cad.gatech.edu (Jason Price) to burble forth:
)*Somehow, I recall that john d. wrote something like this:
( *: Andrew James Hill (ajh...@u.washington.edu) stands accused of alleging:
)*: : A fraternity is a place for men to establish lifelong ties of
( *: : brotherhood with other men,
Which is indirect enough, in itself, but when Jason (you remember
Jason, g'd old gt5076c from gatech) goes:
)*My chapter of Theta Xi is filled with honest, hard working brothers
( *who enjoy each others company.
I am starting to get lost in the haze of euphemism and code-words.
Why not just come out and call a chapter-shack a love-nest? It's
nothing to be aSHAMEd[tm] of. ``Oh, BROTHER, that was HONEST.
Won't you give me another LIFELONG TIE and this time WORK HARD.''
( "In fact, my fraternity disacociates itself from it's brothers who
)commit felonies."
You don't have to misspell f******o on this froup. It's not like we
censor it or anything. Though if this "disacociating" is another
of your pervy rituals, you might want to crosspost a little more
circumspectly. Word might Get Around. [You're welcome in advance.]
)Downright Beckwithian in its obliqueness. (obliquity?)
Speaking strictly de facto ,I'd call it obliquoy.
Speaking of the B- wit, do you suppose CM-U is back in session?
Last year his resolution was to be so vacuocranial as to invite
shuttle-euvanasia. Can he top that? My policy is to be very afraid.
Dan
Hoey@AIC.NRL.Navy.Mil
---
Newsgroups: sci.math
From: hoey@aic.nrl.navy.mil (Dan Hoey)
Date: 04 Jan 1995 17:17:31 GMT
Subject: Re: Number theory question
geoff...@oracorp.com (Geoffrey Hird) asked:
> Do there exist powers 2^n and 3^m such that |2^n - 3^m| = 1,
> other than the two cases 2,3 and 8,9 ?
Yes, the cases 2,1 and 4,3. Other than those,
kevin2...@delphi.com (Kevin Brown) notes:
> This problem is not open, and is not difficult to prove [proof].
which goes to show I should have thought a bit rather than looking up
Guy. Kevin only proves half the statement, though, and somewhat
awkwardly. An easy proof is the following. Inspect to 3^4, and
Consider the smallest larger counterexample.
Case A: 3^m-1=2^n, m even => 3^(m/2)-1 divides 2^n.
Case B: 3^m-1=2^n, m odd => 3^m-1 is 2 mod 4.
Case C: 3^m=2^n-1, n even => 2^(n/2)-1 divides 3^m.
Case D: 3^m=2^n-1, n odd => 2^n-1 is 1 mod 3.
In each case we find a contradiction or a smaller counterexample.
Dan
Hoey@AIC.NRL.Navy.Mil
---
Newsgroups: alt.folklore.urban
From: hoey@aic.nrl.navy.mil (Dan Hoey)
Date: 05 Jan 1995 16:27:43 GMT
Subject: Re: License Plates in Missouri
marzu...@owlnet.rice.edu (Steven Joseph Marzuola) writes:
> I don't think anybody's mentioned Montana, with the rearing horse
> and rider logo in the middle of the letters and numbers. I like it.
I liked it, too. Unfortunately, you then failed to omit such a
mention.
Now I am reduced to appreciating the lack of mention of the senseless
slaughter of the Armenians by the Turks. Or was that arsy varsy?
Dan
Hoey@AIC.NRL.Navy.Mil
ObUL: K1b0 got his -bozing software from S*rd*r *rg*c, who got it out
of an NSA network monitor that was accidentally sold as surplus.
---
Newsgroups: alt.folklore.urban
From: hoey@aic.nrl.navy.mil (Dan Hoey)
Date: 05 Jan 1995 16:29:19 GMT
Subject: Re: Bestiality Male - 7 Percent
> : stated the 7 Percent of the males in the world lost their
> : virginity by acts of bestiality. Does anyone know if this is
> : true, or if they know of the book that I am thinking of.
lberl...@panix.com (Len Berlind) writes:
> _The Seven Percent Solution_, by John Fowles. His basic premise
> was the advocacy of sheep buggery....
Yes, but Fowles was only recasting Charles Lamb's _The Cluck in the
Steeple_, which extolled the erotic possibilites of chickens and their
use as circumspect relief for the lusts of the clergy. A seminal book
that was a great boon to a rural society. Tragically, today's pastors
must choose between cold chickens, warm pigeons, and the youth of the
parish.
Dan
Hoey@AIC.NRL.Navy.Mil
ObUL: Before the advent of factory farming, 43 percent of sheep lost
their virginity to shepherds. Strangely enough, polls on
bestiality revealed that, on average, the sheep had more
partners than the shepherds shept with.
---
Newsgroups: talk.bizarre
From: hoey@aic.nrl.navy.mil (Dan Hoey)
Date: 05 Jan 1995 17:24:28 GMT
Subject: Re: CURSES in english
Michael Laverne <"3...@but.auc.dk"@but.auc.dk> writes:
> Could anyone please send me a list of the worst english/american
> curses. I do not mean the common ones like fuck, shit etc.
I think the worst ones are "getyx", "idlok", "nonl", "vwscanw",
"napms", "tparm", and "vidattr". Another bad one is "draino", but
it's a little too common. Of course, almost anything can be made
worse if you precede it with "mv-" or "mvw-".
Dan "mvwgetstr" Who doesn't regret what he wrote,
Hoey@AIC.NRL.Navy.Mil But sometimes wishes he hadn't told anyone.
---
Article 73497 of alt.folklore.computers:
From: hoey@aic.nrl.navy.mil (Dan Hoey)
Newsgroups: alt.folklore.computers
Subject: Stupid Editor Tricks (was Re: Devastated Utterly)
Date: 05 Jan 1995 18:00:11 GMT
Organization: Navy Center for Artificial Intelligence
In-reply-to: mfinley@mirage.skypoint.com's message of 5 Jan 1995 15:52:34 GMT
mfinley@mirage.skypoint.com (mfinley) writes:
> ...I was operating that day from the old rtin newsreader program. I
> have only used it once or twice -- I could not tell you why the
> program decided to repeat my sentence three times. My belief is that
> it is a clunky text editor....
Not as amazing as the time I saw a post about a television show:
> Tonight! The Dave! 9 pm Eastern. 1 hr 50 min from now.1 hr 50 min from now.1 hr 50 min from now.1 hr 50 min from now.1 hr 50 min from now.1 hr 50 min from now.1 hr 50 min from now.1 hr 50 min from now.1 hr 50 min from now.1 hr 50 min from now.1 hr 50 min from now.
Now don't _everyone_ tell me how it was done.
Dan
Hoey@AIC.NRL.Navy.Mil
---
Newsgroups: alt.current-events.net-abuse
From: hoey@aic.nrl.navy.mil (Dan Hoey)
Date: 06 Jan 1995 00:22:07 GMT
Subject: New spam: Quit Smoking Without Withdrawal!
Seen on rec.puzzles, rec.games.abstract, rec.games.backgammon,
presumably more are on the way.
Anyone who can, please cancel it.
Here's a copy:
> From: Neal Reifsnyder <75364.1...@CompuServe.COM>
> Newsgroups: rec.puzzles
> Subject: Quit Smoking Without Withdrawal!
> Date: 5 Jan 1995 20:35:14 GMT
> Organization: The Cambridge Trust
> Well established, FDA approved drug, eliminates *all* effects of
> nicotine withdrawal within fifteen minutes, allowing you to quit
> once and for all.
> For a 4 page comprehensive text on how to get your doctor to
> prescribe it for you, send *e-mail* reply with "SEND TEXT" in
> the body of your message. The information will be sent
> automatically to the address in your message header.
---
Newsgroups: alt.current-events.net-abuse
From: hoey@aic.nrl.navy.mil (Dan Hoey)
Date: 06 Jan 1995 01:09:23 GMT
Subject: New spam: Quit Smoking Without Withdrawal!
I've verified that the message is a genuine spam. It's been posted to
newsgroups rec.games.bridge, rec.games.backgammon, rec.games.abstract,
alt.recovery, rec.backcountry, rec.boats, rec.food.drink,
rec.gambling, rec.puzzles, rec.sport.golf, rec.models.railroad,
rec.aviation.products, rec.autos.rod-n-custom, rec.autos.marketplace,
rec.autos.misc, rec.food.drink.coffee, rec.collecting.coins,
rec.crafts.marketplace, and rec.crafts.beads.
I've emailed the compuserve.com postmaster (who did, incidentally,
return my message saying that the incense spammer has been flushed)
but it wouldn't hurt to get the cancels going.
Message ID's (from the above "rec" hierarchy groups) are:
<3ehl2e$reu...@mhadg.production.compuserve.com>
<3ehl18$re...@mhadg.production.compuserve.com>
<3ehl0b$re...@mhadg.production.compuserve.com>
<3ehlta$reu...@mhadg.production.compuserve.com>
<3ehkja$sn...@mhadf.production.compuserve.com>
<3ehko1$re...@mhadg.production.compuserve.com>
<3ehktd$re...@mhadg.production.compuserve.com>
<3ehkve$re...@mhadg.production.compuserve.com>
<3ehl62$reu...@mhadg.production.compuserve.com>
<3ehl7b$reu...@mhadg.production.compuserve.com>
<3ehl4r$reu...@mhadg.production.compuserve.com>
<3ehkas$r44...@mhadg.production.compuserve.com>
<3ehk9r$r44...@mhadg.production.compuserve.com>
<3ehk71$r44...@mhadg.production.compuserve.com>
<3ehk8o$r44...@mhadg.production.compuserve.com>
<3ehku9$re...@mhadg.production.compuserve.com>
<3ehkpk$re...@mhadg.production.compuserve.com>
<3ehkro$re...@mhadg.production.compuserve.com>
<3ehkqd$re...@mhadg.production.compuserve.com>
Dan Hoey
Hoey@AIC.NRL.Navy.Mil
---
Newsgroups: rec.puzzles
From: hoey@aic.nrl.navy.mil (Dan Hoey)
Date: 06 Jan 1995 15:17:09 GMT
Subject: Re: Heading northwest
w...@ccm.UManitoba.CA (Barry Wolk) writes:
: ***BEGIN ARCHIVE QUOTE***
: ==> geometry/spiral.p <==
: How far must one travel to reach the North Pole if one starts from the
: equator and always heads northwest?
: ==> geometry/spiral.s <==
: One can't reach the North Pole by going northwest. If one could, then
: one could leave the North Pole by going southeast. But from the Pole
: all directions are due south.
: If one heads northwest continuously, one will spiral closer and closer
: to the North Pole, until finally one can't turn that sharply.
: ***END ARCHIVE QUOTE***
: This "solution" missed the point to the puzzle. What we have here is
: just some quibbling over the wording of the puzzle - we've seen a
: lot of that recently in this newsgroup. It is certainly true that
: you will spiral arbitrarily often around the North Pole, and you
: never actually reach the Pole. However, the path you follow
: "converges" to the Pole, and the complete path happens to have a
: finite length. You are asked to find that length.
No, you seem to have missed the point of the solution (which is, I
grant, not well put). The path in question is a continuous curve of
finite length, but those are not sufficient conditions for the path
of a physical object. I do not support the archives' statement that
there is any positive limit to how _sharply_ a body can turn, but
the _number_ of times a body can turn is certainly finite. Physical
objects do not perform infinite changes of direction, so those
problems that rely on infinite change of direction are inherently
unrealistic. I include also the puzzle of the fly in a train wreck
and the puzzle of the the dog running back and forth between a jogger
and a hiker. They all lead to the question of what direction the body
is going where the infinite turns occur, and there is no answer.
A weaker condition that this path also fails is that it cannot be
traversed (by an idealized mathematical point) in finite time and
with finite acceleration. There are curves that change direction
infinitely many times without requiring infinite acceleration, but
this is not one of them. (ObPuzzle: find such a path).
I do think, though, that the fact that the path length is a continuous
curve of finite length (pi r / sqrt 2) should be mentioned. This can
easily be seen by noting that locally, regions bounded by meridians
and parallels approximate rectangles, and that northwest is 45 degrees
from due north.
Dan
Hoey@AIC.NRL.Navy.Mil
---
Newsgroups: news.admin.misc
From: hoey@pooh.tec.army.mil (Dan Hoey)
Date: 11 Jan 1995 22:37:48 GMT
Subject: Re: Spam in progress (yo, Cancelmoose!) "Quit Smoking..."
In news.admin.misc, Ilana Stern wrote:
>Seen posted separately to (so far) misc.invest, misc.jobs.misc,
>rec.backcountry. Here's a copy of one header. (Text deleted,
>it's an ad for a "new drug!").
sw...@boco.co.gov (Shane Castle) writes:
> Hmmm, only two copies show up on my server, one in misc.health.aids
> and one in rec.backcountry. So I would say that it's not a spam yet...
I found it in rec.games.bridge, rec.games.backgammon,
rec.games.abstract, alt.recovery, rec.backcountry, rec.boats,
rec.food.drink, rec.gambling, rec.puzzles, rec.sport.golf,
rec.models.railroad, rec.aviation.products, rec.autos.rod-n-custom,
rec.autos.marketplace, rec.autos.misc, rec.food.drink.coffee,
rec.collecting.coins, rec.crafts.marketplace, and rec.crafts.beads,
and that was only checking the rec.* groups.
I posted about it on alt.current-event.net-abuse and I mailed the
Compuserve postmaster. I haven't heard back. Did anyone issue
cancels? They might still make a difference for particularly
long-lived spools.
Dan
Hoey@AIC.NRL.Navy.Mil
---
Newsgroups: alt.business.misc, biz.misc, general, misc.forsale
From: hoey@pooh.tec.army.mil (Dan Hoey)
Date: 12 Jan 1995 22:21:16 GMT
Subject: Re: Free Internet Advertising Consultation
toyboy (toy...@gate.net) wrote:
: Ian Kemmish (i...@tdc.dircon.co.uk) wrote:
: : sta...@hollywood.cinenet.net (David Starr) writes:
: : >Want a free consultation over the telephone on your company's Internet
: : >advertising plans? Do make mistakes and have problems in the future,
: : >let us help...
: : Would you accept advice from someone who didn't know advertising
: : in USENET news was a serious breach of Netiquette? Let's just
: : hope he doesn't recommend sending out junk mail.....
: Whose Netiquette on Usenet? Yes, it a serious breach to those from the
: "good" ole days, but times change and with the commerical world paying
: for the expansion ...
Bzzt. Advertizing sleazebag alert! "We paid for the Internet, so we
can fill it with ads."
That's self-serving nonsense. You didn't pay for the net, and neither
did that Starr scum. It's the users paying for it, and no one wants
the ads except the scam-artists.
: - Visit alt.clothing.sneakers and then participate.
: - Finally, get others to participate!
Boycott Usenet advertisers!
Dan
Hoey@AIC.NRL.Navy.Mil
---
Newsgroups: sci.math
From: hoey@aic.nrl.navy.mil (Dan Hoey)
Date: 13 Jan 1995 17:01:37 GMT
Subject: Re: Seeking puzzle solution
ja...@world.std.com (Jane Eisenstein) writes:
> My problem is that given the following 13 sets of numbers:
> { 1, 5 }
> { 2, 6 }
> { 3, 7 }
> { 4, 8 }
> { 1, 5, 8 }
> { 2, 6, 8 }
> { 4, 7, 8 }
> { 1, 5, 7, 8 }
> { 3, 6, 7 }
> { 4, 6, 7, 8 }
> { 2, 5, 6, 8 }
> { 3, 5, 6, 7 }
> { 2, 4, 5, 6, 8 }
> are there 10 or fewer sets of numbers from which these can be derived
> by unioning no more than two together at any time?
This is a variant of the "set cover" problem, which is NP-complete
in the general case. But this instance is small it could easily be
done with a program, and regular enough that it even succumbs to
hand-analysis. In particular, we may restrict our candidate sets
to those that are realizable as intersections of the target sets,
which implies that all of the two-element sets will be included. By
considering which of the three- and four-element target sets are
formed as unions, we find a number of ten-set solutions and a nine-set
solution:
8,67,78, 15,26,37,48, 2568,3567
where the nonprimitive sets are realized as 158=15+8, 268=26+8,
478=48+78, 1578=15+78, 367=37+67, 4678=48+67, and 24568=48+2568. I am
pretty sure that this nine-set solution is essentially unique, in a
sense that excludes some trivial variants.
Dan Hoey
Hoey@AIC.NRL.Navy.Mil
---
Newsgroups: alt.folklore.computers, alt.os.multics
From: hoey@aic.nrl.navy.mil (Dan Hoey)
Date: 13 Jan 1995 22:51:25 GMT
Subject: Re: Interviewing
tom_van_vl...@taligent.com (Tom Van Vleck) writes:
> At the Honeywell Multics group, as part of a serial interview, we
> used to give the candidate a piece of paper & say, "OK, write a
> program."
...
> And you'd be surprised how many people couldn't do it. Couldn't
> write a simple program and talk sensibly about it. They'd huff,
> and bluster, and make excuses, and change the subject, rather than
> actually write some code.
Did anyone ask for a coding form?
Not me, I always program better straight to cards.
Dan
Hoey@AIC.NRL.Navy.Mil
---
Newsgroups: alt.folklore.computers
From: hoey@aic.nrl.navy.mil (Dan Hoey)
Date: 13 Jan 1995 22:57:41 GMT
Subject: Re: "Hacker Books"
d...@pluto.towson.edu (Doug McNaught) writes:
> _Glory Season_, also by Brin--not very computer-related, but Life
> (as in Conway's cellular automata) is a tournament sport.
Hmm. Twenty years after M. A. Foster did it in _The Gameplayers of
Zan_. (or was it _... Xan_?) But Foster is quite off topic here--in
his treatment, computer simulations were prohibited.
Dan
Hoey@AIC.NRL.Navy.Mil
---
Newsgroups: alt.current-events.net-abuse, news.admin.misc, news.admin.policy
Followup-To: news.admin.policy
From: hoey@aic.nrl.navy.mil (Dan Hoey)
Date: 13 Jan 1995 23:25:21 GMT
Subject: Spam continues! Use more cancels! (Re: Spam Cancellation - Run a BBS)
zieg...@va.pubnix.com (Eric Wolfgang Ziegast) writes:
> > Snowhare wrote:
> >> 'Run a BBS' spam canceled from 258 groups.
consisting of 152 alt groups, one biz group, 43 comp groups, 14 gnu
groups, 29 k12 groups, and 19 misc groups.
> Yes, I saw those. We also generated our own cancels (duplicating
> yours by $alz convention).
but more has come. It's hitting the rec hierarchy right now:
rec.art.sf.fandom, rec.arts.sf.misc, rec.arts.comics.misc,... I'll
look further, but it looks like it's still coming. Still dated
Wednesday 11 January, but I think that's about as truthful as the tag
line about it being "an error". Did loa.com *really* ask uunet to
cancel this, or is that another lie?
It doesn't matter, anyone who can should cancel them (using the proper
protocol, of course).
Dan
Hoey@AIC.NRL.Navy.Mil
---
Newsgroups: comp.society.folklore
From: hoey@aic.nrl.navy.mil (Dan Hoey)
Date: 20 Jan 1995 11:13:33 -0500
Subject: Re: HAKMEM
alder...@netcom.com (Richard M. Alderson III) writes:
> Specifically, TLCA (Test Left, Complement, skip Always) does the following:
> Mask the left half of the specified AC with 18-bit effective address
^^^^^^^^^ ^^^^^^^
> Complement all masked bits
> Skip always
> This leads us to the following three-instruction bit swap routine
> (assuming AC 4 and a mask contained in location MASK):
^^^^^^^^^ ^^ ^^^^^^^^
> TRCE 4,MASK
> TRCE 4,MASK
> TRCE 4,MASK
Right the first time. MASK is the number with the bits set, not a
location. (The term "effective address" is a misnomer. It means
"the number that would be used as an address if this instruction
dereferenced an address".) In immediate instructions such as the
T[RL] family, the effective address is the operand itself. For
instance
TRCE A,6
TRCE A,6
TRCE A,6
would swap bits 33 and 34 of accumulator A, and the contents of
location 6 have nothing to do with it (unless, of course, IFE ).
Dan
---
Newsgroups: alt.radio.networks.npr, rec.puzzles
Followup-To: rec.puzzles
From: hoey@aic.nrl.navy.mil (Dan Hoey)
Date: 20 Jan 1995 20:18:07 GMT
Subject: Re: WE puzzler for 1-15-95 [spoiler]
Richard Renner writes:
> NPR Puzzler for January 15, 1995:
...
> The puzzle for next week comes from Sam Lloyd, a puzzler creator
> from the turn of the century. It asks for the shortest route for
> a letter carrier through a certain town. This town has three (3)
> east-west streets and four (4) north-south streets. These streets
> make a total of seventeen (17) blocks in the downtown area. For
> reasons created only in puzzles, the letter carrier can only make
> right turns. Letter carrier must deliver to all the homes on all
> blocks. So as the letter carrier approaches each intersection, only
> straight ahead and right turn are available. The letter carrier
> covers both sides of the street while walking each block. While
> starting from and ending at a place of your choosing, what is the
> shortest route?
A pretty good paraphrase. You didn't mention that the postman serves
both sides of the street as he walks along each block.
Solution follows:
Paraphrased from the letter I mailed in to Liane and Will:
The answer to the puzzle is that the postman must walk at
least nineteen blocks, walking two of the blocks twice. To see
that this is the minimum distance, we may ignore for a moment the
restriction on turns. There are six three-way intersections, and
each must be an endpoint of the postman's path or of a duplicated
section. So there must be at least two duplicated sections
between three-way intersections. Fortunately, there exist two
pairs of three-way intersections one block apart, so the two
duplicated sections can be one block each. By starting at the
three-way on the east or west side and ending up at the other, the
postman can cover all the blocks in a large number of ways, dupli-
cating only the middle north block and the middle south block.
The requirement that the postman make no left turns reduces the
number of solutions to three (up to symmetry). The postman must go
straight at every four-way intersection and must turn at every
two-way intersection. Starting at the west side heading north, he
should turn right either
at the 5th, 6th, 7th, 8th, and 10th,
at the 2nd, 3rd, 5th, 6th, 8th, and 9th,
or at the 2nd, 3rd, 4th, 5th, and 10th
three-way intersection he goes through, as shown below.
_________________ ________ ________ ________ ________
| _____ | | __X__ | | __X__ |
| 6| |7 | | 9| |2 | | 5| |2 |
^ | | | ^ | | | ^ | | |
_____|_____|____ | _____|_____|_____ _____|_____|____ |
10| | | | 5| | | |6 10| | | |
| | | | | | | | | | | |
| 5|__ __|8 | | 8|__ __|3 | | 4|_____|3 |
|________X________| |________X________| |_________________|
I'm very glad that they posed a puzzle in logic and reasoning.
It is much more satisfying than the vocabulary and trivia puzzles.
I hope they can someday find a way to set an on-air puzzle composed
of such problems.
If you look at the solutions, it's interesting to note that the there
are essentially two parts to the town: the inner loop, consisting
of the middle two north-south streets and the central block of the
outside east-west streets, and the outer loop, consisting of the
east-west streets and the outer north-south streets. Transfers
between the two loops occur where they overlap, and the distinction
between the solutions is whether the postman takes the north transfer,
the south transfer, or both.
Perhaps I should also mention that this is one of those puzzles for
which writing a computer program is the wrong solution. Solving it
by hand is both easier and more informative.
Dan
Hoey@AIC.NRL.Navy.Mil
---
Article 74878 of alt.folklore.computers:
From: hoey@aic.nrl.navy.mil (Dan Hoey)
Newsgroups: alt.folklore.computers
Subject: Re: Behavior of sed (was: Re: Interviewing)
Date: 23 Jan 1995 21:50:39 GMT
Organization: Navy Center for Artificial Intelligence
Distribution: usa
In-reply-to: justin@physics20's message of 23 Jan 1995 19:06:34 GMT
Peter Seebach sed:
> >s/\([^ ]*\) \([^ ]*\)/\2 \1/g
> >'a b c d e' should produce?
Cute puzzle.
justin@physics20 (Justin R. Bendich) bleated:
> Why do you make such demands on poor sed? SunOS and VMS (probably
> has same source code) seds produce "b ac d e", which is sed's way of
> crying out for mommy (without the trailing 'g', the behavior is
> correct). IRIX's sed yields "b a d c e". I guess that's "right".
No, the former answer is right. Once you notice that in the second
substitution \1 is "" and \2 is "d" it is easy to see why the correct
result is "b ac d e " (not "b ac d e"). I think I have heard that
some seds refuse to match "[^ ]*" to a null string within s/.../.../g
for fear of an infinite loop. I would expect that detecting the
infinite loop would be so trivial that even a writer of U*x system
software would be able to prevent its occurrence without mangling the
semantics in an obscure and undocumented way. IRIX's behavior
shows that my expectation is too generous. Though I don't think this
is SGI's fault--I suspect they are following some brain-dead standard
designed to preserve the historic lossage, like maggots in amber.
> It's hard to see why you'd want to do this...
Haven't you been paying attention? We are doing this to figure out
who we want to hire. Would you hire someone who couldn't figure out
that sed was doing the right, if nonobvious, thing? How would she
ever debug her sed scripts?
Now if you want an _obscure_ sed hack, analyze:
#! /bin/sh
echo "$*" | sed \
's/./&&/g;s/\(.\).*\(.\)/\2&\1/;s/.\(.\)/\1)(&/g;s/..//;s/...$//
s/(\(.\)\1\1)/-/g;s/(\(.\)\1.)/]/g;s/(.\(.\)\1)/[/g;s/(...)/./g;h;G;P;D' \
| more
I'm told that a patent for the above process was applied for, and that
the application reads in part:
Fantomark strings which, by definition, are imperceptible to man,
animal, or machine, nonetheless have well-defined streaks, which are
ordinary mark strings.... If one assigns NOUGHT to quids and BEING
to quods, and if one calls BIP processing (which amounts to continual
liquidating and quodizing) by the term BECOMING; and calls
liquidating DISSOLUTION and quodizing PASSAGE INTO, then the
intrinsic opposition between quidness and quodness and its continual
resolution through BIP processing is captured by the language:
BECOMING continually mediates the DISSOLUTION of BEING into NOUGHT
and the PASSAGE of NOUGHT INTO BEING.
I offer 57 fantomarks for the cleverest alternative vocabulary
substitions; payment in zorkmids or qatloos is subject to
varying exchange rates.
Dan
Hoey@AIC.NRL.Navy.Mil
---
Article 12496 of rec.arts.sf.fandom:
From: hoey@aic.nrl.navy.mil (Dan Hoey)
Newsgroups: rec.arts.sf.fandom
Subject: Re: Rumors I need clarified about TAFF
Date: 24 Apr 1995 05:59:03 GMT
Organization: Navy Center for Artificial Intelligence
In-reply-to: bap@intersec.demon.co.uk's message of Sat, 22 Apr 1995 11:14:15 +0000
bap@intersec.demon.co.uk (Bernard Peek) writes:
> Any activity that attempts to influence the administrators, other than
> through the ballot, should be made public -- in the interests of TAFF.
> I see such activities as being no better than the ballot-rigging that
> was alleged by the originator of this whole sorry mess.
You're suggesting that administrators may not privately seek advice of
people they trust on issues relating to TAFF administration? You'd
rather it be thrashed out on Usenet, right?
> I can, and do, expect anyone else with the information to make it
> public.
> Until then the integrity of the TAFF system has been compromised.
I tend to believe in greater openness in the process of voting and
administration. But if someone can escalate fragmentary reports of a
disagreement between friends into allegations of compromised
integrity, that's the best argument I've seen for keeping the process
secret, to an even greater degree than has been done here. Until you
came up with this, I thought, "but who would do such a thing?"
Dan
Hoey@AIC.NRL.Navy.Mil
---
Article 4121 of alt.fan.cecil-adams:
From: hoey@aic.nrl.navy.mil (Dan Hoey)
Newsgroups: alt.fan.cecil-adams,alt.usage.english
Subject: Re: Cutting the Mustard
Followup-To: alt.usage.english
Date: 24 Jan 1995 17:14:56 GMT
Organization: Navy Center for Artificial Intelligence
In-reply-to: markg@anshar.shadow.net's message of 23 Jan 1995 13:52:11 -0500
NCJC55A@prodigy.com and nerdbird@pipeline.com, both named Jay Freeman,
ask in different newsgroups of the origin of the phrase:
"can't cut the mustard."
I looked into this some time ago when it came up on the net. While
markg@anshar.shadow.net (Mark G.)'s belief:
> I think it comes from the word 'muster'....
has been mentioned before, I have never seen it suggested by a
linguistic scholar, in a real publication, or accompanied by
historical citation. I believe it is a reinterpretation--something
that was made up when someone misheard the phrase or couldn't explain
it otherwise.
I've also heard it claimed that back in the days of unhomogenized
mustard, it was necessary to stir, or cut, mustard before use, and
that someone who couldn't do that was in pretty bad shape. This
source is someone who is quite well read, and often right, but he
didn't give any citation. I would greatly appreciate hearing of
anything published on this theory.
I checked in Partridge, Spears, the OED, the American Heritage, the
Dictionary of Word and Phrase Origins, and the Random House Dictionary
of American Slang. Ususally it's listed as obscure, but there is at
least one that suggests that it comes from a superlative meaning
something like "The cat's meow"--"That fellow is the mustard on the
dance floor" or something like that. It was current in the 1920's if
I remember right. To cut the mustard would then be to excel, though
that's a far cry from today's usage, in which mustard-cutting is more
of a minimum standard than a maximum.
Good luck checking on this one--write if you find something new.
Dan
Hoey@AIC.NRL.Navy.Mil
---
Newsgroups: alt.usage.english, alt.folklore.science, alt.folklore.computers, sci.engr.manufacturing
Followup-To: alt.folklore.computers, sci.engr.manufacturing
From: hoey@aic.nrl.navy.mil (Dan Hoey)
Date: 25 Jan 1995 16:53:04 GMT
Subject: Re: "Spool" etymology
In a long discussion of the term "spooling" used for buffering in
computer systems, he...@trilithon.com (Henry McGilton) writes, as so
many others,
> I recall SPOOL being an acronym for ``Simultaneous Peripheral
> Operation On Line'' ....
among general disbelief that it's a retroactive acronym. Yet I still
do not believe the name was developed from an acronym, so much as
developed from the word and fitted with an acronym--possibly before
the original usage was publicized. One explanation was posited by
kci...@cpcug.digex.net (Keith Ivey) :
> A reel of magnetic tape is a spool, and "spooling" was originally
> writing information to a tape for storage and reading it back, right?
But there might be a closer meaning. I have heard that "spooling" is
a term that has acquired a specific use in manufacturing engineering.
In a factory with production lines producing a continuous stream of
wire, paper, steel, or whatever, you can sometimes manage to make the
output of one step feed the input of another step. For instance, the
paper coming from a drying process might feed directly into the paper
coating system. This can work if the speeds of the two processes are
matched. But if not, you can only get full use out of both processes
by duplicating the slower line, and then you can't feed directly from
one to another. Instead, you wind the output of the first process on
a spool, which is later unwound into the second process. Given that
this is so similar to what is done with spooling systems in computers,
and that so many of the early system designers were trained as
engineers, I suspect it was named after the industrial process.
Looking a few general and computer dictionaries, I have not found this
derivation, and have seen the acronym derivation claimed. Possibly
this is because few people know the manufacturing term. Perhaps
someone in an early documentation department decided this was too
obscure, and slapped an acronym on it, and it became the "official"
explanation. On the other hand, I may have been given a bum story on
the language of manufacturing engineers, of which I am not one. A
third possibility is that the manufacturing term could have arisen
from the computer usage, which would be quite surprising.
I've added the sci.engr.manufacturing group, in case there is someone
with an old textbook who can verify that "spooling" was used this way
prior to the development of computer spooling systems in the 1950s and
60s. Followups to alt.folklore.computers and sci.engr.manufacturing,
as this is getting somewhat specialized for the other newsgroups.
Dan
Hoey@AIC.NRL.Navy.Mil
---
Newsgroups: alt.usage.english
From: hoey@aic.nrl.navy.mil (Dan Hoey)
Date: 26 Jan 1995 22:03:44 GMT
Subject: Re: Oats, getting them
mcdoug...@acri.fr (Ken McDougall) wrote:
> > > Why does "to get one's oats" signify the achievement of
> > > sexual congress? Are oats an aphrodisiac? Are oat fields
> > > considered to be well suited as a place to indulge? Is
> > > this buried in an old usage of the word? Thanks,
It's often hard to say _why_. ``Sowing wild oats'' is, according to
Hendrickson, a phrase going back to Plautus (194 BC) or before, for
acting foolishly (wild oats being useless as a food crop). The OED
has it attested in English in the 16th century, as well as a ``wild
oat'' meaning the dissolute young man himself.
This is presumably the source of the early 20th century U.S. usages
Spears notes: ``oats'' for semen, ``oat-bin'' for female genitals.
But he also notes 19th century British use of ``greens'' for sexual
activity or release, and ``get one's greens'' for copulation. Quite
possibly ``get one's oats'' (mid-20th century Australian) arose as a
conflation of the two idioms.
I first encountered the phrase on the Beatles' _Let It Be_ album:
``I dig a pygmy, by Charles Audrey on the [deaf aids?]
Phase one, in which Doris gets her oats.''
which I do not understand, other than it being somehow related to ``I
dig a pony'' on the same album.
Dan
Hoey@AIC.NRL.Navy.Mil
---
Newsgroups: alt.usage.english
From: hoey@aic.nrl.navy.mil (Dan Hoey)
Date: 26 Jan 1995 22:11:45 GMT
Subject: Re: "maiden" name question
I have a term for maiden names for men. A womyn of my acquaintance
bridled at a reference to her ``maiden name'', as it categorized the
name by the (relatively inconsequential) fact that she changed it on
marriage. She told me I should refer to her ``birth name''. Issues
of politically correct language aside, this seems to be quite a neat
solution for the unisex case.
c...@oracorp.com (Douglas Harper) writes:
> How about "natal name" for both sexes, and do away with the (offstage)
> presumption of virginity before marriage?
I do not believe that the term ``maiden'' for a young woman presumes
chastity (in any part of the theatre). It is rather the terms
``maidenh{ea,oo}d'' that make the presumption, in a joke at least
as old as Shakespeare.
Dan
Hoey@AIC.NRL.Navy.Mil
---
Newsgroups: alt.religion.kibology, alt.usenet.kooks, talk.bizarre, alt.peeves, alt.stupidity, alt.conspiracy, alt.zima
From: hoey@aic.nrl.navy.mil (Dan Hoey)
Date: 26 Jan 1995 22:29:15 GMT
Subject: Re: who says people from lousiana are stupid???
Russell Shaddox writes:
> I guess learning to spell the names of the 50 states isn't a big
> priority at U.Va....
It's endemic in the South, because of the way they talk.
Why, just yesterday I saw a license plate from "Geauga".
See header for F-ups.
Dan
Hoey@AIC.NRL.Navy.Mil
---
Newsgroups: rec.games.abstract
From: hoey@aic.nrl.navy.mil (Dan Hoey)
Date: 27 Jan 1995 00:17:15 GMT
Subject: Re: Rules,history of renju and other five-in-a-row games
Tommy Maltell writes:
> The two basic _completely free_ rules of all five-in-a-row games are:
> Rule 1. Play alternates between one player who starts the game (in
> Renju called Black because he is playing with black stones on the
> intersections of a board with fifteen vertical and fifteen
> horizontal lines) and another player (usually called White because
> he is playing with white stones).....
> Rule 2. The first player to get an unbroken line of five stones
> (marks) whether vertically, horizontally, or diagonally, wins the
> game.
...
> When the players got stronger they found that playing with the above
> mentioned _completely free_ rules was in great favour of Black (the
> beginner of the game).
No surprise there, but
> It is also proved that there is a sure win for Black when playing
> with _completely free_ rules.
I have heard several claims of this, but I have also heard several
claims that the proofs are seriously lacking in details. That is to
say, that there is an incomplete argument falsely claimed to be a
proof.
Dan
Hoey@AIC.NRL.Navy.Mil
---
Newsgroups: alt.usage.english
From: hoey@aic.nrl.navy.mil (Dan Hoey)
Date: 27 Jan 1995 17:32:35 GMT
Subject: Re: Put in a trick bag?
hoey@aic.nrl.navy.mil (I) asked of a man at a motorcycle rally in the
1950s or 60s, who complains that his old lady tried to put him in a
trick bag.
On the off-chance that receiving a couple of e-mail guesses indicates
interest in the subject, I'll pass on my best current guess. I think
he feels she was treating him like a prostitute treats a customer:
trick=john, bag=category. But it's just a guess, I don't know any
native speakers of this argot.
Dan
Hoey@AIC.NRL.Navy.Mil
---
Newsgroups: alt.folklore.computers
From: hoey@aic.nrl.navy.mil (Dan Hoey)
Date: 31 Jan 1995 00:07:50 GMT
Subject: Re: Wow - This is Great!
stan...@netcom.com (Dan Stangel) was the one who asked "if anyone
could explain" how core memory works.
paul.rog...@nwcs.org (Paul Rogers) replied, perhaps accurately for the
rudeness,
> Yes, but you don't want to know....
djohn...@tartarus.ucsd.edu (Darin Johnson) explained, with less
rudeness but certainly less accuracy:
> They were little donut magnets (or big, depending upon technology).
> Wire coils were wrapped around them, and also they were threaded onto
> a wire lattice. The lattice could detect if a donut were magnetized
> one direction or the other. The coils were used to flip the state.
The sense wires can't detect if the donut is magnetized. They can,
however, detect a _change_ in the magnetization. So the procedure for
reading a core is to flip it in one direction, and see if it changes.
If it changes, you have to flip it back (unless you actually want to
alter the value).
Dan
Hoey@AIC.NRL.Navy.Mil
---
Newsgroups: sci.math
From: hoey@aic.nrl.navy.mil (Dan Hoey)
Date: 31 Jan 1995 22:48:18 GMT
Subject: Re: Bizarre problem in number theory
With regard to numbers that are a multiple of their reverse, I've
called them "palintiples" and have done some investigation of
them. Some of what I've found is on a web page.
m...@hand.timeinc.com (Mark-Jason Dominus) writes:
> But note:
> N=42, M=21 (base 8: N=52, M=25).
> There are may more such pairs than I originally expected.
Many indeed. Also, consider
N=525, M=2625 (base 8: N=1015, M=5101)
The base 8, multiplier 5 palintuples are "recognized" by the
automaton:
6:1
>-------. ,-----------------------. [*]
| 5:1 ^ v 6:2 ^
,----.|,----->[ ]>----. ,-----. ,---->[ ]>-----. |7
|0:0 vv^ ^ 1:0 v ^ 5:2 v ^ 7:6 v v ^
`---<[*] 6:6| [*] [*] |1:1 [*]>---.
v ^ ^ 0:1 v ^ 2:5 v ^ 6:7 v v ^ 7:7|
0| `-----<[ ]<----' `-----' `----<[ ]<-----' `----'
v 1:5 ^ v 2:6
[*] `-----------------------'
1:6
Starting at the left, traversing the arrows, and stopping at an
accepting state [*], you can read off a sequence of arc labels like
5:1 6:1 6:2 7. If you write down the digits before colons, then
the single final digit (if any), then the digits behind colons (in
reverse), you get a number like 5667211, which is five times its
reverse (in base 8), and all such numbers are found in this way. It's
easy to show that all these palintiples are multiples of 3*7. It
seems they are also multiples of 5^3 (so they all multiples of the
palintiple 5101) but I haven't proven it yet.
If you think the above machine is complicated, consider that the
automaton for base 29, multipler 18 has 71 states.
Dan
Hoey@AIC.NRL.Navy.Mil
---
Newsgroups: rec.arts.sf.fandom
From: hoey@aic.nrl.navy.mil (Dan Hoey)
Date: 02 Feb 1995 06:00:04 GMT
Subject: Re: Smileys
hlav...@panix.com (Arthur Hlavaty) writes:
> What? Inquiring old-time fan writers want to know. (Not, I hope, the
> "^H" convention, which requires the reader to count backwards to figure
> out what is being slashed out.)
You'd be surprised at the feats readers will willingly perform to read
fannish cutesiness. But there are plenty of other slashout methods if
you can't stand counting characters--you can use arcane emacs commands
if you want to talk to emacs snobsM-^?gurus, or you can use the
easily-understood Unix abortion\noitroba/convention that you get with
"stty -crterase prterase".
Dan
Hoey@AIC.NRL.Navy.Mil
---
Newsgroups: alt.current-events.net-abuse, news.admin.policy
Followup-To: alt.current-events.net-abuse
From: hoey@aic.nrl.navy.mil (Dan Hoey)
Date: 03 Feb 1995 16:03:40 GMT
Subject: More junk email: Card Call USA
bo...@emile.math.ucsb.edu (Axel Boldt) wrote of Kevin Lipsitz's
recent calling card spam:
: Spammed almost the whole usenet repeatedly with anonymous
: ads (Hi, my name is Anne Nelson...") for a long distance
: calling plan. He was warned by the admin of the anon server,
: then lost his account there and did it again with a new account.
: He told me on the phone that a company called
: Card Call USA, INC.
: 6232 N. 7th ST. #109
: Phoenix, AZ 85014
: Phone: 602-264-7000
: Fax: 602-266-0687
: uses a pyramid-like promotion scheme where every customer
: gets a commission for each new customer they bring and in turn
: for each new customer these new ones bring and so on up to
: level 7.
I recently received e-mail from CCU...@ix.netcom.com, providing a fax
number (703)849-8269 to join in with their scam\macs/program; I don't
know if this is the company itself, Lipsitz, or some other pyramid
junky. The subject: header indicates that they snarfed my address
from a Usenet posting (in alt.business.misc, biz.misc, general, and
misc.forsale). But the message wasn't about my posting, just an ad.
I complained to postmas...@netcom.com, and their customer support
staffer says that CCUSAI has now been told to stop sending unsolicited
email. Be sure to let them know if the situation recurs.
Dan
Hoey@AIC.NRL.Navy.Mil
---
Newsgroups: sci.math
From: hoey@aic.nrl.navy.mil (Dan Hoey)
Date: 03 Feb 1995 17:32:19 GMT
Subject: Re: How many Permutations
jame...@perth.DIALix.oz.au (James Picton-Warlow) writes:
> : mconn...@dunedin.es.co.nz (Martin Connell) writes:
> : > My Daughter wants to know...
> : > How many different 5 letter 'words' can be constructed from the word
> : > 'statistics'
mconnel said: 10 nCr 5 (10!/(10-5)!5! which equals 252 cobinations of
letters.
> Not quite. Firstly, 'words' come ordered, so we want Pr, not Cr.
> Secondly, "statistics" has 10 letters, but some of them are repeated.
> So 10 Pr 5 is too large, since it measures the number of 5-letter words
> assuming all letters distinct. You need to divide by 3! for the "s"s,
> 3! for the "t"s and 2! for the "i"s. Hence 420 possibilities.
Like you said, "not quite". Dividing by 3! 3! 2! would be right if
_all_ the words had 3 s's, 3 t's, and 2 i's, but that's not the
case. In fact, _none_ do.
The only way I see to do it is by case analysis. The cases are
reduced somewhat by first treating s and t alike and a and c alike,
then doing the combinatorics for each group separately.
(5) The number of ways to split the 5 letters into X st's, Y i's, and
Z ac's is 5!/(X! Y! Z!).
(X) The number of ways to split X st's into s's and t's is 2^N minus
the number of ways of choosing more than three s's or t's.
(Z) The number of splitting Z ac's into a's and c's is 1 if Z=0,
otherwise 2.
#s,t #i #a,c| Ways to split | Product
X Y Z | 5 X Z |
-------------+---------------+--------
1 2 2 | 30 2 2 | 120
2 1 2 | 30 4 2 | 240
2 2 1 | 30 4 2 | 240
3 0 2 | 10 8 2 | 160
3 1 1 | 20 8 2 | 320
3 2 0 | 10 8 1 | 80
4 0 1 | 5 14 2 | 140
4 1 0 | 5 14 1 | 70
5 0 0 | 1 20 1 | 20
+--------
Total 1390
I verified this total by printing out all the possibilities (which
helped me fix a bug in my early analysis). I'd like to see a better
solution, though. Can this be done with generating functions?
Dan
Hoey@AIC.NRL.Navy.Mil
---
Newsgroups: alt.usage.english
From: hoey@aic.nrl.navy.mil (Dan Hoey)
Date: 03 Feb 1995 23:05:37 GMT
Subject: Re: argle-bargle
Jerry Young writes:
> For no particular reason, I have been making a list of expressions that
> are made of two repeated words that differ from one another by a vowel or
> a consonant....
A wonderful collection. But how could you miss Hobson-Jobson, a
favorite word of word collectors. A Hobson-Jobson is a
folk-etymological alteration of a borrowed word. It is itself one: it
comes from the Muslim ritual cry "ya Hasan, ya Husayn!" which the
English heard as common surnames.
Speaking of which, a friend of mine claims that "How do you do" is a
Hobson-Jobson for an Old English greeting cognate to "Health to you."
The idea is that the Normans, hearing this greeting, thought it was
the question "How do?" and regularized the grammar. Has anyone seen
research supporting or contesting this, or providing another reason
for asking the odd question "How do you do?"
Dan
Hoey@AIC.NRL.Navy.Mil
---
Newsgroups: alt.usage.english, soc.culture.australian
From: hoey@aic.nrl.navy.mil (Dan Hoey)
Date: 03 Feb 1995 23:22:22 GMT
Subject: Re: Etymology of "Loo"
swa...@ix.netcom.com (John R. Swaney) writes:
> weat...@gov.on.ca (Alison Weatherstone) writes:
> > steve...@bud.indirect.com (Pascal MacProgrammer) writes:
> >> ...Gardy-loo...
> > ... lieux d'aisances ...
> I certainly prefer the second explanation, as "loo" would do
> great violence to the correct pronunciation of "l'eau," but only
> minor violence to the correct pronunciation of "lieux."
Sure, there's mispronunciation either way, but no more than is usual
in cross-language word transfer. I believe both etymologies are
considered possible by experts.
Looking in Cecil Adams and in Eric Partridge, I've found there are
also theories involving "Waterloo Station" (akin to French slang "le
water" for water closet), "Lady Louisa" (whose card was placed on a
lav door by 19th century pranksters), "Room 100" (common European
toilet location), "bordalou" (an 18th century ladies' traveling
convenience) and "leeward". Partridge cites another source with
another half-dozen possibilities.
For an authoritative etymology, consult a dictionary: It says
"orig. uncert" and it's right: the orig. is definitely uncert.
Dan
Hoey@AIC.NRL.Navy.Mil
---
Newsgroups: sci.math
From: hoey@aic.nrl.navy.mil (Dan Hoey)
Date: 07 Feb 1995 23:11:38 GMT
Subject: Re: YASM
ru...@washington.math.niu.edu (Dave Rusin) writes:
: In fact, I wouldn't ordinarily post at all except to follow up the
: knitting theme. The wife of a colleague here does in fact do this (and
: is interested in selling her wares -- contact me if interested): she makes
: caps which are Klein bottles and earbands which are Moebius strips.
: (Well, OK, I just pointed out there is no real Klein bottle in 3D space;
: what she makes is the usual approximation, in which you cut a hole in the
^ ^^^^
: cylinder which allows the two circles to meet in the appropriate
: orientations)....
A HOLE? What a crock! Knitted surfaces are porous, so the Klein
bottle can and should self-intersect properly.
: dave (who really thinks the right hat to make would be a 'cross-cap')
It seems to me this might be a little harder to knit. And even harder
to wear.
Dan
Hoey@AIC.NRL.Navy.Mil
---
Newsgroups: alt.folklore.urban, rec.puzzles, alt.radio.networks.npr
Followup-To: alt.folklore.urban
From: hoey@aic.nrl.navy.mil (Dan Hoey)
Date: 07 Feb 1995 23:42:45 GMT
Subject: What happened to POSH on NPR?
NPR's Car Talk on 28 January posed the hoary old question: ``Why would
the rich want to travel on different sides of the ship going to India
and coming back, and what word did it give rise to.'' Of course, they
are asking for the bogus etymology of "posh" as an abbreviation for
"Port Outward, Starboard Home", which would supposedly give you the
cooler rooms in the days before air conditioning. Of course this folk
etymology is not supported by the historical record. My recollection
is that the probable etymology is from "pash", perhaps derived from
"passionate".
I missed the show on 4 February. Did they get debunked?
Dan Hoey
Hoey@AIC.NRL.Navy.Mil
ObUL: "POSH" is also supposed to be a mnemonic used by British
navigators to tell which way to turn when embarking on the
London-Bombay run. Before it came into use, much delay was
caused by ships taking the long way around. "Cape Horn again,
dash it!"
---
Newsgroups: sci.math
From: hoey@aic.nrl.navy.mil (Dan Hoey)
Date: 14 Feb 1995 22:56:40 GMT
Subject: Re: 6^3 rubiks cube
kpt...@aol.com (KPT Ben) writes:
> ... 7-sided cubes and above can't be constructed physically, at
> least not with square panels. The reason is simple: take the top
> level of the cube, and rotate it 45 degrees. If the cube is cut
> into 7x7 or more equally divided squares, the corner squares at
> 45 degrees will be hovering over empty space, and will fall off.
> (it can't be attached to it's other 2 neighbors due to symmetrical
> considerations).
I believe that is not true, and I don't know what symmetry you are
considering. All you need do is to construct cubies that will stick
to two neighbors, yet will slide when one plane of cubies is rotated
with respect to another. This could be done with dovetail grooves,
for instance. The dovetail grooves will hit the surface of the cube,
but it the groove ends could fit into the blank strip between the
colored squares.
Dan Hoey
Hoey@AIC.NRL.Navy.Mil
---
Newsgroups: alt.radio.networks.npr
From: hoey@aic.nrl.navy.mil (Dan Hoey)
Date: 21 Feb 1995 13:32:07 GMT
Subject: Re: WE Puzzler for 2-12-95
e...@panix.com (Eric Berlin) writes:
> Next time you answer the puzzle, guy, you might not want to give
> the answer away to everybody else on the Internet.
As always, guy, I embargoed my puzzle answer until after the
submission deadline, which is the close of business on Thursday. I
certainly agree, guy, that publishing an answer before the deadline
is not a good idea.
Dan Hoey
Hoey@AIC.NRL.Navy.Mil
---
Newsgroups: alt.folklore.urban
From: hoey@aic.nrl.navy.mil (Dan Hoey)
Date: 22 Feb 1995 00:23:59 GMT
Subject: Re: The Simpsons and drain water direction
v064m...@ubvms.cc.buffalo.edu writes:
> gberkow...@BIX.com writes:
> >The 2/19/95 Simpsons episode deals in large part with
> >which way the water goes down the drain.
> >Lisa categorically states that it's CCW in the Northern,
> >and CW in the Southern hemisphere, due to the
> >Coriolis Effect. Due to Bart's mischief, the family
> >ends up "down under", where the toilets do indeed flush
> >CW, except in the American Embassy, where an enormous
> >contraption is used to ensure that the toilet works
> >"The American Way".
Particularly nice was the way that when you flushed it, it started
going clockwise, then the incredibly loud and powerful jets kicked in
and switched the direction.
> Maybe this is been hashed over 2 million times, but the coriolis
> effect is quite small in toilet sized bodies of water. I think it
> will drain in whichever direction the jets under the rim are pointed.
Yes it has, and yes it is, but no, it won't necessarily. In most
toilets of my acquaintance, the jets don't start before the draining
starts and the eddy forms, and they aren't strong enough to turn it
back. Some years ago I read a research report about the formation of
bathtub eddies. Currents from the last disturbance of the water will
continue to be strong enough to overpower the Coriolis force for many
hours. So the real answer to which way the flush goes probably has to
do with which way you are threaded (or rifled?).
TeeVee has picked up on urban legends in a big way. I remember Hill
Street Blues ran the catnapper's restaurant, the molesting dentist,
alligators in the sewers, and one or two others I can't dredge up
just now.
Also, there was a movie on HBO over the weekend, _Sonoma Cafe_ or
something like that, that had homeless people being kidnapped and
their organs stolen. They didn't wake up in a strange hotel room,
though. Come to think of it, they had a new Get Smart with the same
theme. They're everywhere.
Dan
Hoey@AIC.NRL.Navy.Mil
ObUL: The difference in Coriolis effect between the Eastern and
Western hemispheres is the reason it is more efficient for the
English to drive on the left side of the road.
---
Newsgroups: talk.bizarre
From: hoey@aic.nrl.navy.mil (Dan Hoey)
Date: 22 Feb 1995 22:35:16 GMT
Subject: Re: Rone's Bone
wal...@eehpx43.cen.uiuc.edu (waldby julian f) writes:
> n...@essex.ac.uk (Neil Dewhurst) writes:
> |> ... "rone" is pronounced "ron-e" as he suggests, there is the
> |> opportunity for pseudo rhyme along the lines of "on-e", "gone-e",
> |> etc.
I thought it had a long O. Moany groany, hark? Rone was a warrior,
way-ay-ay.
> |> I think perhaps Mr Dorsey has overstated the case
> |> somewhat. "5150" rhymes with "shifty", which has certain
> |> possibilities,...
> Part of the problem is that I always pronounce 5150
> five-one-five-oh, so you are both wrong, and thrifty nifty, and even
> shifty do not rhyme with it.
Might too.
A teebo who often posts nive-oh
Ideas even if a bit shive-oh,
Went upscale and tone
On his high polo pone
And wrote too much to be called thrive-oh.
> |> klu...@netcom.com (Scott Dorsey) writes:
> |> >Personally, I would recommend you pick another victim whose
> |> >account name is easier to deal with, if you find it impossible
> |> >to improve your poetic skills.
Does that rhyme with "fudge" or with "spooge"? Or both?
Dan "rhymes with coy" Hoey
---
Newsgroups: talk.bizarre
From: hoey@aic.nrl.navy.mil (Dan Hoey)
Date: 22 Feb 1995 22:36:05 GMT
Subject: Re: In the perfect world
Zed writes:
> There'd be a box on your driver's license you could check to indicate
> you wanted your body donated to a necrophiliac.
Donated? I don't want my body to be just a one-night stand. I want
my body to have a _relationship_ with a necker, not just a empty
physical thing.
Dan
Hoey@AIC.NRL.Navy.Mil
---
Newsgroups: alt.cyberpunk, alt.atheism.satire, alt.conspiracy, alt.satanism, talk.religion.misc, alt.fan.bill-gates, alt.christnet
Followup-To: alt.cyberpunk
From: hoey@aic.nrl.navy.mil (Dan Hoey)
Date: 23 Feb 1995 00:36:50 GMT
Subject: Re: DUMB BITCH - I copy....
Continuing to abuse talk.bizarre, dje...@telerama.lm.com (Sourcerer) writes:
: Yong-Mi Kim (k...@cs.umd.edu) wrote:
: > Sourcerer writes:
: > >On Wed, 22 Feb 1995, Yong-Mi Kim wrote:
: > [my email, which is included in a post, without my permission,
: > that contributes to the crossposting woes the poster is so
: > concerned about]
: By including a list of newsgroups you incited the daemon.
Well, here's your newsgroups back, mister d. And don't post email, it
isn't nice. Remember, daemons are not above the law. In your case,
they are below the slime.
: > >AFAIK, the
: > >bombings originated in talk.bizarre. We don't care, anyway.
:
: > If you were to check the subject line, that particular thread
: > (nor the originator of the post) is not native to talk.bizarre.
: > Insofar as I can tell, she lives mostly in alt.fan.bill-gates,
: > and has already been voted Kook of the Month in alt.usenet.kooks.
: You are suggesting that no one from talk.bizarre has participated in
: these threads? I don't read talk.bizarre, alt.fan.bill-gates or
: alt.usenet.kooks. I'd have to read hundreds of subj. lines, Newsgroups,
: and Follow-up To's every few days, in order to show you all the
: consideration you havn't shown us.
So you don't know where the threads come from, but you figure you can
blame Yong-Mi for them. Moron.
: > I think you are damaging your cause by failing to show any concern
: > or civility to the readers of newsgroups other than alt.cyberpunk.
: I have no cause except to a) create the killfile for alt.cp that captures
: all the crossposts, no matter how they morph and metastatize, for as many
: newsreaders as I can (mostly for the newbies who are being discouraged),
Do it. Then you won't be bothered, and maybe you will stop being
obnoxious about it.
: and b) get the attention of the rest of you, to think before you crosspost.
How about the people who do think before we cross post, who are
waiting for you to STFU. Why doth thou sniff at the haemorrhoid of
thy neighbor and ignore the suppurating boil on thine own anus?
: As for civility, to my knowledge only one denizen of alt.cp has (once)
: posted to *any* of dozens of threads that are at present actively being
: crossposted to alt.cp, *nor* has any of these threads been initiated by
: anyone known to be a 'regular' on alt.cp.
Your self, of course.
: So, of course, *our* or *my* civility is in question.
Yours. I haven't seen anyone else presume to speak for anyone else's
abused group.
: Right.
Right.
: --
: (__) Sourcerer
Idiot.
: /(<>)\ O|O|O|O||O||O Welcome to Hell, here's your accordion.
Cute, real cute. Larson, right?
: \../ |OO|||O|||O|O
: || OO|||OO||O||O
You think this loreward is pretty? My cat has a box of oddly-shaped
clay granules you can spread all over your floor.
Dan Hoey
Hoey@AIC.NRL.Navy.Mil
---
Newsgroups: rec.puzzles
From: hoey@aic.nrl.navy.mil (Dan Hoey)
Date: 24 Feb 95 17:30:32 GMT
Subject: Boodle Phil moiven?
The following appeared in 1985 on a mailing list, together with some
Prolog code. The apparent poser of the problem claimed it was forged,
and my questions about it were unanswered. Would anyone care to
investigate the mystery? The problem itself is quoted below, but
instead of Prolog code I provide you an English explanation, rot13'd
in case you want to puzzle it out for yourself
The puzzle:
> 1. Lucy sod'n pho Abner, kips Abner sod'n pho Lucy.
> 2. Hubert bink ptui Phil, kips Hubert bink ptui Abner.
> 3. Lucy sod'n pho Hubert myt Myrtle sod'n pho Hubert, kips Lucy pock
> matoo Myrtle.
> 4. Lucy pock matoo Leonard myt Leonard pock matoo Myrtle, kips
> Myrtle moiven Lucy. Leonard moiven Hubert myt Hubert bink ptui
> Phil, kips Leonard moiven Phil.
> 5. Leonard sod'n pho Phil. Boodle Phil moiven?
================================================================
The explanation:
1. "Xvcf" zrnaf fbzrguvat yvxr "gurersber." Guvf zrnaf gung "fbq'a
cub" vf flzzrgevp--vs V "fbq'a cub" lbh, gura lbh "fbq'a cub" zr.
2. Guvf jnf genafyngrq gb zrna gung vs lbh "ovax cghv" nalbar lbh jvyy
"ovax cghv" rirelbar.
3. "Zlg" zrnaf "naq". Fb "Cbpx zngbb" vf gur eryngvbany fdhner bs
"fbq'a cub"--vs gjb crbcyr rnpu "fbq'a cub" gur fnzr guveq crefba,
gura gurl "cbpx zngbb" rnpu bgure.
4. "Zbvira" vf n yvggyr zber pbzcyvpngrq. "Zbvira" vapyhqrf gur
eryngvbany fdhner bs "cbpx zngbb"--vs gjb crbcyr rnpu "cbpx zngbb"
gur fnzr guveq crefba, gura gurl "zbvira" rnpu bgure. Ohg "zbvira"
vf rkgraqrq ol "ovax cghv", va gur frafr gung vs lbh "zbvira"
fbzrbar jub "ovax cghv"f n guveq crefba, gura lbh "zbvira" gung
guveq crefba nyfb.
5. Gur chmmyr cbfrq vf, jub qbrf Cuvy "zbvira"?
================================================================
Extras:
A second interesting puzzle is: Can you invent meanings for "sod'n
pho", "bink ptui", "pock matoo", and "moiven" that make these axioms
reasonable?
And third--does anyone know where the problem is from, or even what
language it is in? If you have the translation, please mark it as a
spoiler to avoid interfering with the second puzzle.
Dan Hoey
Hoey@AIC.NRL.Navy.Mil
---
Newsgroups: talk.bizarre
From: hoey@aic.nrl.navy.mil (Dan Hoey)
Date: 24 Feb 1995 22:24:34 GMT
Subject: SS misreading (Re: WE MISS YOU! *sniff*)
I keep misreading *sniff* as SNTF.
Not that I miss silver. In fact, the reminder is annoying. But odd.
Dan (...who doesn't regret writing it, but
Hoey@AIC.NRL.Navy.Mil sometimes wishes he'd never told anyone.
How long before someone reposts it this time?)
---
Newsgroups: alt.current-events.net-abuse
From: hoey@aic.nrl.navy.mil (Dan Hoey)
Date: 26 Feb 1995 23:48:48 GMT
Subject: Re: tronics spam in a.s.s.d and a.f.p
xt...@blaze.trentu.ca (Kate Gregory)
> ...Surely asking for the FAQ (even in a group like misc.kids where
> the FAQ's are literally never posted, though an index to them is
> posted every week) is by definition on topic.
No, asking for the FAQ is on topic only in news.newusers.questions, so
you can be told to look in news.answers, or on one of the archive sites.
Jumping into a newsgroup you know nothing about and asking for the FAQ
is rude, and not on topic (unless you are dealing with a newsgroup
whose topic is the dissemination FAQ lists).
Dan Hoey
Hoey@AIC.NRL.Navy.Mil
---
Newsgroups: alt.folklore.urban
From: hoey@aic.nrl.navy.mil (Dan Hoey)
Date: 27 Feb 1995 00:45:37 GMT
Subject: Re: University of Wisconsin nude posture photos
v140p...@ubvms.cc.buffalo.edu (Daniel B Case) writes:
> The First Lady was photographed, according to the NYTMag story, at
> Wellesley, not Yale (she went to Yale Law School, not Yale College)
> where, by the time she was a freshman, women were allowed at least to
> cover up part of their bodies.
And just what part might that be? Or did they have a choice?
Dan "left eyebrow" Hoey@AIC.NRL.Navy.Mil
ObUL: In a recent interview, the President discussed the tendency to
make jokes about him. "I've become a genre. They make a joke
about everything I do, every meeting with another leader, from
Boris Yeltsin to Bob Dole." And what was the most unusual role
played by Bob Dole in a Clinton joke? "That'd be...."
Punchline omitted.
---
Newsgroups: talk.bizarre
From: hoey@aic.nrl.navy.mil (Dan Hoey)
Date: 28 Feb 1995 22:48:02 GMT
Subject: Re: So, Frankie is sleeping with Kimberly now.
b...@jfwhome.funhouse.com (Babs Woods) writes:
> So, Frankie is sleeping with Kimberly now.
> Well, it isn't quite what you think....
This puzzle is in the rec.puzzles archive, in a news.answers near you.
: Archive-name: puzzles/archive/logic/part3
: ==> logic/situation.puzzles.p <==
: Jed's List of Situation Puzzles
: 2.21. Bob and Carol and Frankie and Kimberly all live in the same
: house. Bob and Carol go out to a movie, and when they return,
: Kimberly is lying dead on the floor in a puddle of water and glass.
: It is obvious that Frankie killed her, so we had to take care of him.
Don't bother, we know the answer. IWTYWHTKYT.
(...who doesn't regret creating it, but
Dan sometimes wishes he'd never told anyone.
Hoey@AIC.NRL.Navy.Mil How long before someone reposts it this time?)
---
Newsgroups: talk.bizarre
From: hoey@aic.nrl.navy.mil (Dan Hoey)
Date: 02 Mar 1995 22:22:54 GMT
Subject: S s scansion flames (Re: MST3K rulz... / ANABOLIC ALTERNATIVES)
In article to half a zillion groups, explictly followed up to all of them,
fran...@ucssun1.sdsu.edu (ConHugeCo Pres-qu-homme) writes:
= Dr. Mellow (drmel...@catt.ncsu.edu) wrote:
= : I don't remember the name, but the best MST3K episode was the Sandy Frank
= : number about how apes are the rulers in the future. It also featured the
= : documentary called "Why Johnny Doesn't Care." My friends, this is classic.
=
= TIME OF THE APES!!!
=
= Tarkis Brainlab Five
=
= Hail Tom Servo
What? 4-5-4?
Not even close, clown.
Keep your day job.
_ . _ . _ . _ . _ . _ . _ . _ . _ . _ . _ . _ . _
meanwhile, c...@netcom.com (C J Silverio) writes:
+ m p w
+ moves files without ceasing
+ the minutes tick past
Ceej's 5-6-5
Offsets my January
Slight overhaiku.
Dan Hoey ( ... who doesn't regret creating it, but
Hoey@AIC.NRL.Navy.Mil sometimes wishes he'd never told anyone. )
---
Newsgroups: alt.folklore.urban
From: hoey@aic.nrl.navy.mil (Dan Hoey)
Date: 05 Mar 1995 21:38:10 GMT
Subject: Re: Just a little off at the knee, please
tr...@eskimo.com (OTIS) writes:
> TAMPA, FLORIDA (AP):
> A Tampa hospital where doctors accidentally cut the wrong foot off a
> patient began a policy yesterday requiring staff to write the word
> "No" on patients' limbs that are not to be cut off.
It would be safer to write PHI GAMMA DELTA on the limbs that are not
to be removed. Then the doctors would truly be compelled not to
destroy the sacred letters.
The only problem would be that everyone who went to the hospital for
adenoids or liposuction would come out with PHI GAMMA DELTA written on
their arms and legs. They could never after wash their limbs, and if
they ever subsequently got gangrene medical science would be helpless.
Dan
Hoey@AIC.NRL.Navy.Mil
ObFraternUL: The true, official name is PHIDELTAGAMMA.
You wouldn't call your country a "c ount ry", would you?
---
Newsgroups: sci.math
From: hoey@aic.nrl.navy.mil (Dan Hoey)
Date: 05 Mar 1995 21:47:47 GMT
Subject: Re: 0^0 should equal 1. Right???
mdek...@fwi.uva.nl (Martijn Dekker) writes:
> d...@kaa.informatik.rwth-aachen.de (David Kastrup) wrote:
> :... An empty product, however, is 1,
> :like an empty sum is 0. Everything else does not make sense.
> no, an empty product is not equal to 1, it is in some cases
> *defined* as 1 for convenience. same for ths empty sum being 0.
Your distinction is vacuous. It is "convenient" in any ring with an
identity, as are all the systems we are discussing here. And so it
is defined to be 1 "for convenience" just as conveniently as 1+1 is
defined to be 2. It is ridiculous to try to make 0^0 to be less
identical to 1 than 2-1.
Dan
Hoey@AIC.NRL.Navy.Mil
---
Newsgroups: rec.games.abstract
From: hoey@aic.nrl.navy.mil (Dan Hoey)
Date: 06 Mar 1995 16:34:23 GMT
Subject: Re: rubick's cube moves wanted
spenf...@aol.com (SPENFaux) writes:
> If you are interested in cubing, try...................
> cube-lov...@life.ai.mit.edu
Almost. Try
cube-lovers-REQU...@life.ai.mit.edu
That's where you send mail to get added to the list, and get the
information about where to find the archives. The "cube-lovers@..."
address is only for the discussion about the cube; sending
administrative requests there is not appreciated.
And remember, rec.games.abstract is for discussion of abstract
two-person games. Not Rubiks cube, that goes in rec.games.puzzles.
(and not the game of Life, that goes in comp.theory.cell-automata.)
(and not role-playing games, they go in rec.games.role-playing.misc.)
(and not GIFs, they go in alt.binaries.pictures.misc.)
Dan
Hoey@AIC.NRL.Navy.Mil
---
Newsgroups: rec.puzzles
From: hoey@aic.nrl.navy.mil (Dan Hoey)
Date: 07 Mar 1995 13:48:29 GMT
Subject: Re: Triangle Puzzle
Lee Shere writes again:
> Start with an equilateral triangle.
> Draw two lines from each vertice [vertex] to trisect
> the opposite side, forming an irregular hexagon
> in the center of the triangle.
> What is the ratio of the area of triangle to
> the area of the hexagon (in whole numbers)?
Stitch admired the puzzle so much I guess
you might like seeing a solution. I wrote most of this when Lee Shere
posed the problem here in 1992.
In addition to drawing two lines from each vertex to trisect the
opposite side, let us draw an altitude from each vertex to bisect the
opposite side. The bisectors cut the central hexagon into six
congruent triangular pieces. I will calculate the area of one of
those pieces.
Take such a piece that shares a side of the hexagon formed by a line
from vertex A of the original triangle. The piece is the difference
of two long thin triangles with vertex A, both of which have as sides:
1. the line from A to a point trisecting the opposite side,
2. the line from A to the midpoint of the opposite side, and
3. the altitude from a side adjacent to A.
By the symmetry of the original triangle, there are just two kinds of
such long triangles, and the difference of their areas will be the
area of a sixth of the hexagon.
Consider the ratio into which the triangle's altitude is cut by a line
from a vertex to the opposite side
+B
/:\
/ : \
/ : ,\E
/ D;' \
/ ,': \
/ ,' : \
/,' :H \
A+'------+-------+C
The line AE has a vertical rise 1-BE/BC as far as that of AB, and
covers a horizontal distance 1+BE/BC times as far as AB, so
DH/BH=(1-BE/BC)/(1+BE/BC), and the area of triangle ADH is
(1-BE/BC)/(1+BE/BC) times the area of triangle ABH, which is half of
ABC. So as BE/BC assumes the values 1/3, 1/2, and 2/3, the area of
ADH assumes the values 1/4, 1/6, and 1/10 the area of ABC. The two
interior triangles with bases on BH then have areas 1/4-1/6=1/12 and
1/6-1/10=1/15 of the area of ABC. The difference of the two triangles
is then 1/60 of ABC, so the ratio of the hexagon to ABC is 1/10, QEI.*
Here are a few interesting features of this puzzle.
1. The triangle need not be equilateral: the shape of the triangle
does not affect the outcome. The equilateral case is just handier
to solve, because of its symmetry.
2. Suppose we divide each sides of the triangle into 2n+1 parts: how
big is the central hexagon then? Prove that it's a unit fraction
of the triangle.
ObPuzzle: What fractions of the original triangle can appear as
regions in a triangle cut by lines from vertices to evenly-spaced
points on the opposite side?
Dan Hoey
Hoey@AIC.NRL.Navy.Mil
* Look it up.
.
quit
---
Newsgroups: rec.puzzles
From: hoey@aic.nrl.navy.mil (Dan Hoey)
Date: 07 Mar 1995 21:54:13 GMT
Subject: Re: Triangle Puzzle (spoiler)
gsg5501@Msu.oscs.montana.edu writes:
> The problem, stated Feb. 20 and then again Feb. 28, went something
> like this: take an equilateral triangle, trisect the angles. What's
> the ratio of the area of the triangle to the area of the irregular
> hexagon formed in the middle?
Well, _that_ problem hasn't been stated before here. All the previous
problems have involved trisecting a _side_ of the triangle with
lines from the opposite vertex. I posted the answer to that this
morning.
Oddly enough, it is the answer you give.
But the problem you pose, of trisecting the _angles_ to form a
hexagon, is also interesting, though the answer is not rational.
Using the method of my previous message, it's easy to see that if the
ratio of the central segment of each side to the side is X, then the
area of the hexagon is (72 / (9 - X^2)) - 8 times the area of the
triangle. For an equilateral triangle whose angles are trisected,
X=Sqrt[3] Tan[Pi/18], so the hexagon is
(24 / (3 - Tan^2[Pi/18])) - 8 ~ 0.0837781
times the area of the triangle.
ObPuzzle: Express that in radicals (i.e., without trig functions).
Dan
Hoey@AIC.NRL.Navy.Mil
---
Newsgroups: sci.math, rec.puzzles
Followup-To: rec.puzzles
From: hoey@aic.nrl.navy.mil (Dan Hoey)
Date: 07 Mar 1995 22:14:13 GMT
Subject: Re: Sequence Problem
blkti...@usis.com (Black Tiger) writes:
> The sequence 1,2,4,8,16,31,... is created by taking a circle and putting
> n points on the circle and connecting each point to every other point by
> straight lines to form the maximum number of regions.
> Any suggestions on determining the formula that will produce this
> sequence?
Sure, it's C(N,0) + C(N,2) + C(N,4).
C(N,0) is 1, because you start out with one region,
C(N,2) is the number of lines, because you add a region every time
you draw a line, and
C(N,4) is the number of intersections, because you add a region
every time the interior of two lines intersect.
That also explains why it starts out looking like 2^(N-1).
ObPuzzle: Put N points on a sphere, and cut the interior with every
plane determined by three of the points. What is the
maximum number of interior regions?
Dan
Hoey@AIC.NRL.Navy.Mil
---
Newsgroups: sci.math
From: hoey@aic.nrl.navy.mil (Dan Hoey)
Date: 08 Mar 1995 17:13:51 GMT
Subject: Re: Improper Integrals
ssor...@calstatela.edu (Stephen Sorkin) writes:
> |> When you evaluate an improper integral that diverges to positive
> |> or negative infinity you break it into two improper integrals.
> |> However, if both of the sections is divergent even with one
> |> opposite the other (e.g., Integral of x^-1 from -1 to 1) it is
> |> still said to be divergent. Shouldn't the two sections cancel
> |> out to zero as they are mirror images? Why should it not be
> |> allowed to establish a 1-1 correspondence between points on
> |> opposite sides?
One important feature of the integrable functions is that they are a
vector space over the reals--they can be multiplied by a constant, and
added to each other. When you start allowing functions like F(x)=1/x
you will probably also allow G(X) = 2/x - 1/|x|, which, while not
symmetric, can still have its positive and negative parts placed in
1-1 correspondence. But then 2 F(x) - G(X) = 1/|x|, which diverges in
both directions.
Dan
Hoey@AIC.NRL.Navy.Mil
---
Newsgroups: sci.math
From: hoey@aic.nrl.navy.mil (Dan Hoey)
Date: 09 Mar 1995 23:28:46 GMT
Subject: Re: Pi
kova...@mcmail.cis.mcmaster.ca (Zdislav V. Kovarik) writes about 22/7:
> (1) It's a very good approximation for the size of its denominator,
> though. You can verify that to get a better approximation, you
> have to increase the denominator to 99 (the fraction being 311/99).
> A fraction is understood to have an integer numerator and a positive
> integer denominator.
I think you overlooked 179/57, 201/64, 223/71, 245/78, 267/85, and
289/92.
Dan
Hoey@AIC.NRL.Navy.Mil
---
Newsgroups: alt.discordia, alt.religion.kibology, alt.illuminati
From: hoey@aic.nrl.navy.mil (Dan Hoey)
Date: 10 Mar 1995 16:38:02 GMT
Subject: Re: LONGEST KNOWN PALINDROME
s...@course3.harvard.edu (Michael Soss) writes:
> Not bad, but Mitch Poplack posted (a while ago) a better one.
> Here it is:
> A man, a plan, a caret, ..., a calamus, a dairyman, a bater, a
> canal--Panama!
Well, I don't know who this Mitch Poplack is, but that isn't his
palindrome, it's mine. I discovered it in 1984.
When I let it be posted to the net, I was identified as the author.
But there seem to be a some people out there who have some objection
to giving credit where it is due, and they cut my name off it and
repost it. I consider this to an objectionable behavior, and I ask
that people who observe it let the offenders know of my objection.
So please don't post it without citing me as its author.
Dan Hoey
Hoey@AIC.NRL.Navy.Mil
---
Newsgroups: talk.bizarre
From: hoey@aic.nrl.navy.mil (Dan Hoey)
Date: 13 Mar 1995 17:48:48 GMT
Subject: T.B.Dream
It's only every year or so that I remember a dream into consciousness,
excluding the addict's wet dream where I start smoking again (I only
remember those when I try to figure out how long it's been since my
last cigarette). So it's not so suprising this is the first time I
remember a dream of talk.bizarre.
It was in a book. Short articles, bound in cardboard. I remember one
was a poem. Written in Greek, and someone had marked the feet with
pencil. Pity I don't read Greek. And there was one article that was
humorous, and perhaps obscene, and it mentioned Gooley. Until that
point, I hadn't realized it was a book of t.b excerpts. I turned to
the cover, and the jacket design looked fairly interesting, but I woke
up before I figured out what the title was.
Where did this book come from? I've never BoBbed, I've never met
anyone I knew from t.b. (though I saw someone wearing a newt/anvil
shirt at Disclave last year. I wonder who that was.) My best guess
is I must have seen this book at a party and started skimming it, and
absent-mindedly walked off with it.
So if anyone's missing their t.b. anthology, please claim it. And
does anyone know the subject line that the Greek poem was posted
under, so I can wastefully look it up in the archives?
Dan
Hoey@AIC.NRL.Navy.Mil
---
Newsgroups: rec.arts.comics.alternative, rec.arts.comics.marketplace
Followup-To: rec.arts.comics.marketplace
From: hoey@pooh.tec.army.mil (Dan Hoey)
Date: 20 Mar 1995 23:37:13 GMT
Subject: Re: [PUBLIC SERVICE ANNOUNCEMENT] Comic Book Club Available On-Line
nminfo@netmart.com wrote:
: PS. I have nothing to gain from this post and am directly associated
: with Imagination Ink, this is simply a PSA to the comic book
: community of the net
Yeah, sure. Who are you? "nminfo@netmart.com", the company that runs
the market. "Come look at my ads! No purchase required!"
I don't mind hucksters that stay in the marketplace groups. But when
you start flogging your stuff on r.a.c.a it's not a PUBLIC SERVICE
ANNOUNCEMENT, it's a SLEAZY AD IN A NON-MARKETPLACE GROUP.
Boycott abusive advertisers!
Dan Hoey
Hoey@AICR.NL.Navy.MIl
---
Newsgroups: alt.folklore.urban
From: hoey@aic.nrl.navy.mil (Dan Hoey)
Date: 21 Mar 1995 16:44:02 GMT
Subject: Re: Oops! surgical mistakes
vanho...@netcom.com (William E. VanHorne) writes:
> spin...@aston.ac.uk writes:
> >I read recently about the man who went into surgery and had the
> >wrong leg amputated. Has anyone else any surgical mishaps they
> >want to share?
> Apropos of such things, this morning's Columbus Dispatch has a short
> article reporting that a woman scheduled for a masectomy had the
> wrong breast removed....
Those were on CNN over the weekend, too, along with the one about
turning off the wrong respirator. I imagine, now that the topic has
slithered into the news, that we are going to get dozens of medical
mixup stories. These are going to be harder to pin down than most
urban legends, since the hospitals cite privacy concerns when asked to
confirm or debunk the stories.
I'm told (by an F) that I have a FOAF who needed surgery on her left
knee. Before going in to surgery, she marked the knees, writing
"WRONG KNEE" dexter and "CUT HERE" sinister (bar goolies). The medics
actually started to prep the wrong knee, so she had to tell them to
read the directions. (Were they really making a mistake, or just
pulling her leg?) But seriously, the F claims this story is genuine.
So if you will be my friend, this a FOAFOAF story for you.
ObUL: A bill before the Florida legislature attempts to prevent
medical mixups by requiring doctors to paint large X marks over the
eyes of comatose patients before turning off life-support machinery.
The action is supported by the undertakers' lobby, whose clients
expect to charge high fees to cosmetically erase the marks.
(Cartoonists are planning to sue for trademark infringement.)
Dan "mixed up at birth" Hoey@AIC.NRL.Navy.Mil
---
Newsgroups: rec.puzzles
From: hoey@aic.nrl.navy.mil (Dan Hoey)
Date: 21 Mar 1995 16:49:04 GMT
Subject: Re: Enigma's Puzzle 1 (SPOILER + quibble puzzle)
enigm...@aol.com (Enigma GB) writes:
> The correct answer is Prancer...Rudolph is not correct because he
> couldn't "play any of their reindeer games."
> Remember the eligibility "claus"e!
Very good reason! Now if anyone can explain why the TENTH reindeer is
eliminated, or even the (humorous) name of that reindeer, please don't
post it until
THURSDAY MARCH 23
to give the other puzzlers a chance.
Dan
Hoey@AIC.NRL.Navy.Mil
---
Newsgroups: alt.radio.networks.npr
From: hoey@aic.nrl.navy.mil (Dan Hoey)
Date: 21 Mar 1995 23:40:04 GMT
Subject: Shamrocks?
holl...@is.nyu.edu (holland) writes:
Well, nothing, really.
The question of course is, did the All Things Considered shamrocks
bloom in time? I was away from my radio for St Paddy's.
Dan
Hoey@AIC.NRL.Navy.Mil
---
Newsgroups: alt.religion.kibology, alt.society.neutopia
From: hoey@aic.nrl.navy.mil (Dan Hoey)
Date: 21 Mar 1995 23:40:28 GMT
Subject: Re: Pancakes
wedns...@tezcat.com (Wednesday) makes pancakes:
> I mean, they're light and fluffy and stuff.
> BUT THEY'RE AN INCH THICK!
I think the Prince of Danemark noticed the same thing about his mom's
makeup. But he made her come anyway. Who ever said Shakes wasn't a
lovolutionary?
Dan
Hoey@AIC.NRL.Navy.Mil
---
Newsgroups: rec.puzzles
From: hoey@aic.nrl.navy.mil (Dan Hoey)
Date: 23 Mar 1995 17:32:06 GMT
Subject: Re: Enigma's Puzzle 1 (SPOILER + quibble puzzle)
hoey@aic.nrl.navy.mil (I) wrote:
> Now if anyone can explain why the TENTH reindeer is eliminated, or
> even the (humorous) name of that reindeer....
Thanks to Brian Gordon for reminding me to send you the spoiler.
The tenth reindeer in the song is "Olive, the other reindeer."
I imagine Olive was disqualified for name-calling.
Dan
Hoey@AIC.NRL.Navy.Mil
---
Newsgroups: alt.folklore.urban, alt.folklore.computers
Followup-To: alt.folklore.computers
From: hoey@aic.nrl.navy.mil (Dan Hoey)
Date: 26 Mar 1995 07:17:25 GMT
Subject: Re: Emergency Broadcast tone
ak...@lafn.org (Tim Shell) writes:
> I heard a news report not long ago that the US EBS was being
> scrapped and reporaced with one that can actually turn on your radio
> remotely. Anybody have any guesses as to how this is supposed to be
> accomplished?
The principle is pretty straightforward. They've been using a tone
from the keyboard to turn on Macintosh computers for years.
Dan
Hoey@AIC.NRL.Navy.Mil
ObComputerUL: Lately, even L.E.D. displays tend to be run by
microcomputers--and one of them has a surprising bug in the firmware!
It seems that a certain fairly common sequence will cause the ucode to
execute its end-of-program trap (a no-op--you don't need to do a lot
of cleanup on an L.E.D.). But the bug can actually be observed in
a batch of the chips that were accidentally released with debugging
firmware, in which the ucode trap flashes "uEnd" in the lights. I saw
a Coke machine with a debugging chip once. It's an amazing sight to
see an embedded processor crying out for help.
Dan
Hoey@AIC.NRL.Navy.Mil
---
Newsgroups: alt.folklore.urban
From: hoey@aic.nrl.navy.mil (Dan Hoey)
Date: 26 Mar 1995 08:22:53 GMT
Subject: Plutonium debunked in the Atlantic
The new Atlantic Monthly has a good article on the myth of plutonium
as the "deadliest substance known to man". The explanation seems
to be that in the 1940s and 1950s it was difficult to get people
concerned about industrial toxins. Administrators in the nuclear
program exaggerated plutonium's toxicity in hopes of averting the
kind of carelessness that led watch-dial painters to lick their
radium-contaminated brushes.
The article also mentions a long-term study that monitors the health
of 26 workers who inhaled plutonium dust. After 40 years, all but
three are still alive, a survival rate that is considerably better
than the population as a whole. They call themselves the "UPPU" club
because traces of plutonium can still be measured in their urine.
There was also an article about the plutonium myth in the American
Scientist magazine last month, essentially debunking the fears that
plutonium smuggled out of the former Soviet Union could have poisoned
Munich's water supply.
Dan Hoey
Hoey@AIC.NRL.Navy.Mil
---
Newsgroups: alt.folklore.urban
From: hoey@aic.nrl.navy.mil (Dan Hoey)
Date: 28 Mar 1995 22:24:41 GMT
Subject: Re: Plutonium debunked in the Atlantic
> hoey@aic.nrl.navy.mil (I) wrote:
> > The new Atlantic Monthly has a good article on the myth of plutonium
> > as the "deadliest substance known to man". The explanation seems to
> > be that in the 1940s and 1950s it was difficult to get people
> > concerned about industrial toxins. Administrators in the nuclear
> > program exaggerated plutonium's toxicity in hopes of averting the
> > kind of carelessness that led watch-dial painters to lick their
> > radium-contaminated brushes.
kei...@guvax.acc.georgetown.edu replies:
> No doubt there's a bit of straightening-out to be done on that score,
> but the explanation above (I am responding only to this post - have
> not yet checked the source) is simple double-talk.
To attack a statement on the basis of no information is intellectually
dishonest. In case you need specific reference, the article is
"Atomic Overreaction" by Jeff Wheelwright, in the April 1995 _Atlantic
Monthly_, p. 26 ff. Come back when you know what you're talking
about.
My article also mentioned "Plutonium's Bad Rep" by David Schoonmaker,
in the March-April 1995 _American Scientist_, pp. 132-33, which
discussed the press's exaggeration of the mass-contamination dangers
in the Munich plutonium-smuggling case.
> Pu *is* "deadly" and "a small amount can cause cancer in all humans
> who ever lived and their dogs", in the sense that the radiation dose
> likely to cause cancer if delivered to a small area of tissue is
> available from a small particle of Pu in less than a person's
> lifetime.
If you cited your sources, I might suspect you have some facts,
instead of just parroting someone's exaggerated parroting of someone's
exaggeration.
> Thus it is true that Pu dust, if powdered and inhaled by
> the entire population, would be a bad thing,
Of course, Pu dust *was* powdered and inhaled by the entire
population. As Wheelwright notes that atmospheric bomb testing has
left everyone over the age of 30 with plutonium oxide particles in
their lungs, in amounts that are detectable on autopsy. But they
don't seem to be dying of it.
> ...and the total amount of dust necessary to cause this bad thing,
> if the theoretical minimum were used and none were wasted, is a
> fairly small lump.
A lump bigger than a breadbox? Smaller than your brain? Try some
numbers, and compare them with the workers in the "UPPU club", who
were exposed to significant amounts of Pu dust in the 1940s--more, for
instance, than Karen Silkwood--and were still healthier than the
average population after forty years.
[ As an aside, Joel Furr last year claimed that while soluble Pu salts
are highly carcinogenic, Pu dust is not a carcinogen. He cited his
father, a nuclear physicist and radiation safety officer, for the
claim that the body deactivates Pu particles by encysting them in scar
tissue (It doesn't take much to stop alpha particles). Wheelwright's
article, though, states that the major cancer danger of Pu is as
submicron dust particles that are trapped in the lungs. He also says
that George Voelz's study of dust-exposed workers measured Pu in their
urine forty years later. Someone who's got the Pu data might be able
to explain the apparent contradiction; I can't. ]
> ... It's also true that you don't care much if everyone else in the
> world gets cancer or not if *you* happen to be the one who got
> dosed; this may be a reason to contain Pu whether or not it's likely
> to get snuffled up by the entire world in small doses.
I don't know what you are blithering about, but it sure is blither.
John Donne and I care a whole lot about the general population's
health, quite aside from our own. But I do not think that the
population's health is served by the exaggeration of tiny risks at the
expense of realistic ones.
> [ The scare over plutonium is overblown.... ] But the noise above is
> just nonsense. The *nuclear industry* deliberately overstated the
> dangers of its own materials out of humanitarian concern for those
> stupid workers who just wouldn't stop gobbling the stuff up no
> matter how much protection they were given? Nonsense.
It's easy to say "noise" and "nonsense", especially through your hat.
Wheelwright says that it was indeed very difficult to keep nuclear
workers from careless and intentional self-contamination. Perhaps if
you deign to read his article you will have some informed comment.
> The common claim about Pu is a way of stating the fact that it is
> dangerous in very small amounts, and that relatively large amounts
> of it are available in reactor waste and bomb materials. This is an
> important point to make, though it has certainly also become
> something of a scare tactic. But however that point arose and how
> it got used or misused, it certainly was not just a public service
> message gone awry on the part of nuclear waste managers who only had
> our health and safety at heart.
Do you think the Manhattan Project managers were trying to kill the
workers? Of course they warned the workers to take precautions. And
being more fearful of having the warnings ignored than about having
them exaggerated, they were probably not too careful about starting
the folklore. I certainly don't think they were the only ones who
exaggerated the Pu hazard, but it looks like they may have given it
the first push toward insertion into the Guinness Book of Records.
> Note the clever perversity of the claim: whatever (tiny, *tiny*)
> danger there is from radioactives, ordinary citizens brought it on
> themselves. The nuclear industry was merely trying to protect them,
> and used that harmless substance, plutonium, as a kind of
> Redi-Kilowatt safety messenger to spread the word about the bad habit
> of eating unstable isotopes. And now those silly environmentalists
> just *wouldn't* understand and got themselves all worked up about
> cancer and all that. Uh-huh.
Uh-huh, I note your "claim". If you were aiming for clever
perversity, you accomplished it. Of course, we were talking about the
Atlantic article, and my remarks on it, which have nothing to do with
this clever little piece of perversity you invented.
No one denies that plutonium is carcinogenic. The point is that
plutonium is not the extreme example of a carcinogen that has become
current in folklore (Remember folklore? This is a newsgroup about
folklore.) And Wheelwright's article makes what seems to me a good
case for the origin of the exaggeration, in the nuclear worker safety
programs of the 1940s and 50s. That is an noteworthy claim, from a
folkloric standpoint.
On the other hand, your presentation of unexamined, unsupported,
innumerate propaganda is not a statement _about_ folklore, it is
itself folklore.
As for sla...@logica.com (Graham Slapp)'s comment,
> I don't suppose the original posters address ending 'navy.mil' is
> coincidental?
My posting from the Navy Artificial Intelligence Center on my off
hours has as much to do with the Atlantic Monthly article as (I
imagine) Graham's posting from Logica UK Limited has. Which is to
say, none. I generally don't follow the custom of claiming not to be
a "Navy spokesman" in all my messages, because that always has been,
and should be, the default assumption. I have, though, noticed a
marked increase in the number of newsweasels who, lacking substantive
comment, want to make something of it.
Dan Hoey
Hoey@AIC.NRL.Navy.Mil
ObUL: (Tb) We're all gonna die!
---
Newsgroups: sci.chem
From: hoey@pooh.tec.army.mil (Dan Hoey)
Date: 1995/03/31
Subject: How to Succeed!
Have you seen the posters for the revival of "How to Succeed in
Businees Without Really Trying"? There's one printed in Time Magazine
this week. Hilarious!
Dan Hoey
Hoey@AIC.NRL.Navy.Mil
---
Newsgroups: sci.math
From: hoey@aic.nrl.navy.mil (Dan Hoey)
Date: 1995/04/05
Subject: Re: Adics
will...@broccoli.princeton.edu (William Schneeberger) writes:
> rob...@cs.caltech.edu (Robert J. Harley) writes:
> >So-called "adics" are the invention of a lunatic crackpot who calls
> >himself "Ludwig Plytonium" or "Archimedes Plutonyum". Please
> >ignore his ranting and raving.
> No, adics are not the invention of Plutoniam, but are legitimate
> mathematical constructs. The quick-and-dirty description of the
> so-called "p-adic numbers" (usually taken with p prime when Plutonion
> is not involved) is as follows:
The "p-adic" numbers are well-known, sure, but the "adics" are what
the aforesad crank decided to fixate on when someone showed him the
10-adic counterexamples to FLT. I guess he figured that "10-adics"
didn't sound general enough, and he didn't understand the problems
with throwing all the numbers in the same pot.
Rob continues:
> > If your newsreader allows you to filter out messages, I recommend
> > that you do so. For instance with rn under Unix, add this line:
> > /Plotunium/a:j
> > to ~/News/sci/math/KILL.
If you're going to use kill files, you ought to be more careful. For
instance, you would have filtered out *this* article, and any article
with a hostname named after the chemical element, or that mentions the
element. Maybe that's what _you_ want, but you are advertising this
to sci.math as a way of dropping the crackpot, and they should know
they may be dropping a lot more.
I would suggest the lines:
/^From:.*polutonium@/h:j if you want to drop the original toxic waste,
/polutonium@/a:j if you want to drop the recycled toxic waste.
Of course, different newsreaders use different formats for kill files.
Take a look in the kill-file faq if you're not sure of yours.
Dan Hoey
Hoey@AIC.NRL.Navy.Mil
---
Newsgroups: sci.chem
From: hoey@aic.nrl.navy.mil (Dan Hoey)
Date: 1995/04/05
Subject: Re: Smoke Bomb
hahn@newshost (Karl Hahn) writes:
> kravi...@oeto1.oeto.pk.edu.pl (Pawel Krawczyk ) writes:
> > : I neeed to know how to make smoke bombs for a martial arts show. Must
> > : be non-toxic, and does not matter what color it is. (Preferrably
> > : cheap in price to make too.). :-)
> > The best one i've checked:
> > Zn (powder)....................25%
> > ZnO (used e.g for painting)....20%
> > MgO ............................5%
> > CCl4 (tetrachloromethane, solvent)..50%
> > you mix all the solid ingredients first, then place them in a can.
> > Then add the CCl4 (should be thoroughly mixed with the solid
> > mass) - just before you want to fire it. It can be difficult to
> > make it burn, the best way is to use a bit of black gunpowder as
> > an initiator. Gives a lot of thick, snow-white smoke.
> CCl4 is rather hard to get in the U.S. these days because it is a
> toxic hazard. But tetrachloroethylene ought to work just as well.
CCl4 has been hard to get in the U.S. since the 1960s--it was banned
for consumer use due to high toxicity. But more recently it has been
internationally hard to get for industrial or research use, because it
was banned as one of the chemicals that is destroying the ozone layer.
So by making smoke bombs with it, you can poison yourself while you
help destroy the world. You will also be *wasting* it--there are
presumably research people who will pay a pretty penny for your
remaining stock, if you have any. Or you can be good, and turn it in
to the toxic disposal crew.
Dan Hoey
Hoey@AIC.NRL.Navy.Mil
---
Newsgroups: misc.education.science
From: hoey@aic.nrl.navy.mil (Dan Hoey)
Date: 1995/04/11
Subject: Radiation reputations (Re: Americium in smoke Detectors)
> mu...@erich.triumf.ca (FRED W. BACH , TRIUMF Operations) writes:
> # ... If this isotopt were called plutonium, people would
> # freak out, because of it's bad reputation. But since this isotope
> # is called Americium, like "America", foolish people think it's
> # motherhood and apple pie. Yet the regulations are similar in my
> # books up here.
cbet...@unlinfo.unl.edu (clifford bettis) writes:
> ... I agree that the relative reputations of Am and Pu is a puzzle.
> I think it must have to do with the weapons application of Pu as
> boooth elements represent a similar health risk in small quantities.
There is a possible explanation in the article "Atomic Overreaction"
by Jeff Wheelwright, in the April 1995 _Atlantic Monthly_, p. 26 ff.
During the Manhattan project, chemists did not want another episode
like that of the radium watch painters. Plutonium seemed like another
possible danger, but they could not quantify it, and it took a lot to
scare people about industrial contamination back then. So they told
the workers it was possibly the most dangerous substance on earth.
Eventually this got picked up by the _Ripley's Believe it or Not_ and
the _Guinness Book of World Records_, and a folk legend was born.
People demonstrate against space launch of radiothermal generators
because they contain plutonium. When a half kilogram of plutonium
smuggled from Moscow was confiscated in Munich, the press was full of
wild surmise about whether Munich could have been held ransom by
terrorists threatening to toss it in the reservoir. In "Plutonium's
Bad Rep" (March-April 1995 _American Scientist_, pp. 132-33), David
Schoonmaker checked up and found that the N.Y. Times and L.A. Times
had no scientific source for these stories. He calculates a 40
millirem exposure per person (assuming even dispersal through the
water supply) as compared to 300 millirem annual background exposure.
I'm not suggesting that plutonium is not dangerous, just that its
hazards have apparently been exaggerated out of proportion. I think
Americium escaped this fate, not because of its cute name, but because
it was not produced in quantities in the 1940s and 1950s.
As for the Americium source in a smoke detector, it sure seems like a
good idea to keep it sealed unless you know what you're doing--which
the teacher and student apparently did not. I would really like to
hear how that episode turned out.
Dan Hoey
Hoey@AIC.NRL.Navy.Mil
---
Newsgroups: news.groups, news.admin.policy
From: hoey@aic.nrl.navy.mil (Dan Hoey)
Date: 1995/04/11
Subject: Re: RESULT: news.admin reorganization passes
dob...@info.usuhs.mil (Michael Dobson) writes:
> The existance of the .misc group is a side-effect of the reorg that
> gave us the current news.admin.* newsgroups. Whenever a discussion
> group is promoted to a hierarchy with multiple topics, a .misc group
> is created as a catchall for the remaining topics.
That's nonsense. Leaving the original group around with the original
name, is a perfectly good idea. It works just fine for sci.math and
sci.physics to have the miscellaneous group named for the hierarchy.
Apparently, though, whenever someone issues an RFD to split a group,
the hierarchy-control storm troopers jump on you and say THOU SHALT
RENAME THE ORIGINAL GROUP TO .MISC, and the RFD author usually goes
along.
Someone even has a micro-FAQ to tell you why you need a .misc group.
They claim it simplifies news administration (which it doesn't), that
it reduces cross-posting (which it doesn't), that it helps maintain
the self-respect of the other subtopics (which it doesn't), that it
clarifies the hierarchy (which it doesn't), and that it keeps INN
happy (so fix INN already). They even claim it makes the filesystem
work better, which is the silliest idea I ever heard of (is anyone
running a unix without inode cacheing any more?)
No, what happens is that the miscellaneous topics get relegated
to a subgroup, and then whenever someone comes up with a truly
miscellaneous post, they post it to every newsgroup in the hierarchy
(because nobody reads the misc group any more).
Just say no to .misc!
Dan Hoey
Hoey@AIC.NRL.Navy.Mil
---
Newsgroups: rec.puzzles
From: hoey@aic.nrl.navy.mil (Dan Hoey)
Date: 1995/04/11
Subject: Re: Strings
kra...@peanuts.informatik.uni-tuebingen.de (Armin Krauss) asks
> What is the longest repetition-free string one can built with {0,1,2} ?
Where a "repetition"--more usually called a "square"--is two nonempty
equal adjacent consecutive substrings.
d...@sjfc.edu (Dan Cass) thought he had an example of an infinite
string, but Lou D'Andria found his example was faulty.
I found a paper on squares in binary sequences by Aviezry S Fraenkel
and R Jamie Simpson in
_The Electronic Journal of Combinatorics_, Volume 2.
It includes the statement:
It has been shown many times that there exist infinite squarefree
_ternary_ sequences. See e.g., Thue (1912), Morse and Hedlund
(1944), Hawkins and Mientka (1956), Leech (1957), Novikov and
Adjan (1968), Pleasants (1970), Burris and Nelson (1971/72),
del Junco (1977), Ehrenfeucht and Rozenberg (1983). (Currie
(1993) wrote: ``One reason for this sequence of rediscoveries
is that nonrepetitive sequences have been used to construct
counterexamples in many areas of mathematics: ergodic theory,
formal language theory, universal algebra and group theory, for
example...''.) Actually, Thue (1912) showed more: there exists a
doubly infinite squarefree ternary sequence which also avoids the
2 triples $a_1a_3a_1$ and $a_2a_3 a_2$. See Berstel (1992, \S4.2)
for an exposition of the full result, and Berstel ($\ge$ 1995) for
an English translation of Thue's papers.
The cited references are:
1. J. Berstel (1992), Axel Thue's work on repetitions in words, in:
_Series Formelles et Combinatoire Algebrique_ (P. Leroux and
C. Reutenauer, eds.), Publ. du LACIM, Vol. 11, Universite de
Quebec, a Montreal, pp. 65-80.
2. J. Berstel ($\ge$ 1995), Axel Thue's papers on repetition in
words: an English translation, Publ. du LACIM, Universite de
Quebec, a Montreal.
3. S. Burris and E. Nelson (1971/72), Embedding the dual of
$\pi_{\infty}$ in the lattice of equational classes of semigroups,
_Algebra Universalis_ 1, 248-153.
4. J.D. Currie (1993), Open problems in pattern avoidance,
_Amer. Math. Monthly_ 100, 790-793.
5. A. del Junco (1977), A transformation with simple spectrum which
is not rank one, _Canad. J. Math._ 29, 655-663.
6. A. Ehrenfeucht and G. Rozenberg (1983), On the separating power of
EOL systems, _RAIRO Inform. Theor._ 17, 13-22.
8. D. Hawkins and W.E. Mientka (1956), On sequences which contain no
repetitions, _Math. Student_ 24, 185-187.
12. J.A. Leech (1957), A problem on strings of beads, _Math. Gaz._
41, 277-278.
14. M. Morse and G.A. Hedlund (1944), Unending chess, symbolic
dynamics and a problem in semigroups, _Duke Math. J._ 11, 1-7.
15. P.S. Novikov and S.I. Adjan (1968), Infinite periodic groups I,
II, III, _Izv. Akad. Nauk. SSSR Ser. Mat._ 32, 212-244; 251-524;
709-731.
16. P.A.B. Pleasants (1970), Non-repetitive sequences,
_Proc. Cambridge Phil. Soc._ 68, 267-274.
19. A. Thue (1912), Uber die gegenseitige Lage gleicher Teile gewisser
Zeichenreihen, _Norske Vid. Selsk. Skr., I. Mat.
Nat. Kl. Christiania_ I, 1-67.
Dan Hoey
Hoey@AIC.NRL.Navy.Mil
---
Newsgroups: rec.food.cooking, alt.folklore.urban
Followup-To: alt.folklore.urban
From: hoey@aic.nrl.navy.mil (Dan Hoey)
Date: 1995/04/18
Subject: Re: SWANS ARE PROTECTED HERE
Carl Zetie writes:
> I (mis)spent my undergraduate years at Peterhouse and
> don't recall ever seeing swan on the menu....
It's hard to believe it hasn't been mentioned in this thread yet, but
consider the last line of the limerick:
The swans is reserved for the dons.
which explains your observation, or lack thereof.
Dan
Hoey@AIC.NRL.Navy.Mil
---
Newsgroups: rec.puzzles
From: hoey@aic.nrl.navy.mil (Dan Hoey)
Date: 1995/04/20
Subject: Re: aba string problem
finlowk@vax.sbu.ac.uk writes:
> Here's a problem which we were going to put on the first year
> combinatorics exam, but much to our surprise it turned out to be far to
> complicated:
> How many of the strings of ten characters using the two character
> alphabet { a,b } contain the sub-string aba?
It's not that complicated. I'm not sure your students should be able
to get it under the time pressure of an exam, but I'm surprised you
didn't get it when you set out to post about it.
Let's count is the number of strings of various lengths _lacking_ the
substring "aba", forming a recurrence by counting the ways of adding a
new letter to the end of the previous strings. In order to avoid
generating strings ending in "aba", we must keep a separate count of
strings ending in "ab", and in order to count those, we must also keep
a count of strings ending in "a".
So of the abaless strings of length n, let us suppose there are Nab(n)
ending in in "ab", Na(n) ending in "a", and Nx(n) others.
Immediately,
Nab(0)=Na(0)=0, Nx(0)=1,
Nab(n+1)=Na(n),
Na(n+1)=Na(n)+Nx(n) (Remember not to add an "a" to the Nab(n)),
Nx(n+1)=Nx(n)+Nab(n).
It's easy enough to use this recurrence to make up a table of Nab(n),
Na(n), Nx(n) for n=0,...,10, but there is a better way. Representing
the recurrence by a matrix, we have
[ 0 0 1 ]
[ Nab(n), Na(n), Nx(n) ] [ 1 1 0 ] = [ Nab(n+1), Na(n+1), Nx(n+1) ]
[ 0 1 1 ]
If we name the matrix A, we need to compute A^10:
[ 0 1 1 ] [ 2 3 2 ]
A^2 = A A = [ 1 1 1 ]; A^4 = A^2 A^2 = [ 2 4 3 ];
[ 1 2 1 ] [ 3 5 4 ]
[ 3 5 4 ] [ 49 86 65 ]
A^5 = A^4 A = [ 4 7 5 ]; A^10 = A^5 A^5 = [ 65 114 86 ];
[ 5 9 7 ] [ 86 151 114 ]
[ Nab(10), Na(10), Nx(10) ] = [ Nab(0), Na(0), Nab(0) ] A^10
= [ 0, 0, 1 ] A^10
= [ 86, 151, 114 ].
So the answer is 2^10 - 86 - 151 - 114 = 673.
> If you can answer the previous question (and I can't) why not try
> the more general question: how many of the strings of length N using
> a K character alphabet contain the substring w?
The same method works.
ObPuzzles: 1. Why are there only five distinct values in A^n?
2. What limits do Na(n)/Nab(n) and Na(n)/Nx(n) approach?
3. Will generating functions yield a closed form for these
functions?
Dan
Hoey@AIC.NRL.Navy.Mil
---
Newsgroups: rec.arts.sf.fandom
From: hoey@aic.nrl.navy.mil (Dan Hoey)
Date: 1995/04/24
Subject: Re: Rumors I need clarified about TAFF
b...@intersec.demon.co.uk (Bernard Peek) writes:
> Any activity that attempts to influence the administrators, other than
> through the ballot, should be made public -- in the interests of TAFF.
> I see such activities as being no better than the ballot-rigging that
> was alleged by the originator of this whole sorry mess.
You're suggesting that administrators may not privately seek advice of
people they trust on issues relating to TAFF administration? You'd
rather it be thrashed out on Usenet, right?
> I can, and do, expect anyone else with the information to make it
> public. Until then the integrity of the TAFF system has been
> compromised.
I tend to believe in greater openness in the process of voting and
administration. But if someone can escalate fragmentary reports
of a disagreement between friends into allegations of compromised
integrity, that's the best argument I've seen for keeping the process
secret, to an even greater degree than has been done here. Until
you came up with this, I thought, "but who would do such a thing?"
Dan
Hoey@AIC.NRL.Navy.Mil
---
Newsgroups: rec.puzzles
From: hoey@aic.nrl.navy.mil (Dan Hoey)
Date: 1995/05/05
Subject: Re: partial spoiler Re: NPR puzzle for 4-30-95
elk...@ramanujan.harvard.edu (Noam Elkies) writes:
> Richard Renner writes:
> > The puzzle for next week notices that there are eight numbers on a
> > telephone that have letters. Two is a, b and c; three is d, e and
> > f; and so on to nine, which is w, x and y. Can you spell an eight
> > letter word using the letters on a telephone dial without
> > repeating a number? ...
> There are several other suitable words. This puzzle is too easy to
> solve with an online wordlist and pidgin C:...
But it's even easier than that-- this is one of those problems that
is so trivial it can be solved with a pipeful of greps:
grep '^........$' words | grep -v '[qz]' \
| grep -v '[abc].*[abc]' | grep -v '[def].*[def]' \
| grep -v '[ghi].*[ghi]' | grep -v '[jkl].*[jkl]' \
| grep -v '[mno].*[mno]' | grep -v '[prs].*[prs]' \
| grep -v '[tuv].*[tuv]' | grep -v '[wxy].*[wxy]'
Keypunch that one for your next playtime!
Dan
Hoey@AIC.NRL.Navy.Mil
---
Newsgroups: rec.puzzles
From: hoey@aic.nrl.navy.mil (Dan Hoey)
Date: 1995/05/08
Subject: Re: An interesting Moebius band problem
ber...@fantasyfarm.com writes:
> The current issue [April, 1995] of Mathematics magazine had an interesting
> item about an unusual way to make a Moebius band: get some paper in the
> shape of a 'T'....
> ....
> . .
> -----------------
> | |
> | |
> -----.-----------
> . .
> ...
> This is an edge-on view of the center bar's path.
As Dave Ring pointed out, this is not a Moebius strip. Actually, its
topology is that of a Moebius strip with a bridge. A Moebius strip is
formed by identifying two opposing segments of a disk:
................
^ |
| |
|................v
while the T-figure adds two more identified segments:
......===>......
^ |
| |
|......===>......v
It's not surprising there is only one surface, since adding
identifications can't turn a nonorientable surface orientable. It's
interesting that there is only one edge, though. I don't know of a
concise characterization for the identifications that leave you with
one edge.
Dan
Hoey@AIC.NRL.Navy.Mil
---
Newsgroups: sci.math
From: hoey@aic.nrl.navy.mil (Dan Hoey)
Date: 1995/05/09
Subject: Re: Combinations. Whoopee.
prax...@aol.com (Praxxix) writes:
> How many multiples of 3 between 100 and 1000 can be formed from the digits
> 1,4,5,6, and 8?
> Mike Laussade
Take an ordinary six-faced die, and change the 1, 2, and 3 to
6, 8, and 1, respectively.
Then you can read off a three-digit multiple of three by starting at
any face and reading clockwise around one of its corners.
All you need to do is figure out how many ways you can read numbers
off the die, and why this procedure gives you the right answer.
Dan
Hoey@AIC.NRL.Navy.Mil
---
Date: Tue, 09 May 95 12:11:02 -0400 (EDT)
From: Dan Hoey
To: Cube Lovers
Subject: Re: more on the slice group
Jerry Bryan writes:
I don't yet understand why Mike's position is a local maximum in the
full cube group. But assuming it is, it is not only the shortest
local maximum, it is the first local maximum which is not
Q-transitive (i.e, we have |{m'Xm}|=24, hence we have |Symm(X)|=2,
and the size of the symmetry groups for Q-transitive positions
must be divisible by 12.).
No, the 4-spot pattern is also a local maximum at 12 qtw, although its
symmetry group is of order 16. Jim Saxe and I reported this on 22
March 1981, in "No short relations and a new local maximum".
Dan
Hoey@AIC.NRL.Navy.Mil
---
Article 2785 of alt.humor.best-of-usenet:
From: hoey@AIC.NRL.Navy.Mil
Newsgroups: alt.humor.best-of-usenet
Subject: [alt.religion.kibology,alt.folklore.urban,etc.] Re: ATMs
Date: 11 May 1995 14:54:36 GMT
Approved: ahbou-mod@acpub.duke.edu
Originator: sht123@alf.usask.ca
From: rsholmes@hydra.syr.EDU (Rich Holmes)
Newsgroups: alt.religion.kibology,alt.folklore.urban,alt.conspiracy,alt.comics.batman
Subject: Re: ATMs
hello_mum@voxel.com (Anne Marsden) writes:
>Are there any hackers on this newsgroup who can tell me how to get the
>machine to make Yen instead? I hear it's much more useful. At least
>it's much more useful to the Japanese.
Simple. At least in the US, it works like this: When asked for your
PIN, instead of your usual PIN you enter JPAN (i.e. 5726). Initially
it will tell you this PIN is invalid and reject your card. Go ahead
and put the card back in and repeat the procedure 7 times. The 7th
time it will accept the JPAN PIN and will print your money as yen.
You get a very favorable exchange rate, plus since the data
connections between Japan and the US are unreliable, it doesn't check
to see if you're overdrawing your account when you use yen.
Here are some PINs for other currencies:
Swiss franc SWIS (7947)
British pound BRIT (2748)
German mark GERM (4376)
Your currency choice is active not only for that transaction, but for
any transactions you make from then on at any ATM (use your normal
PIN). To change back to US dollars use the above procedure with the
PIN USAM (8726).
Which leads me to a really funny joke you can play on someone. Steal
a friend's ATM card and use it with the following PIN: MONO (6666).
Then put the card back. From there on, when your friend tries to use
an ATM, they'll get Monopoly money!!! I did this to my roommate last
year. It was HILARIOUS.
--
Postings to alt.humor.best-of-usenet reflect what the submittor considers to be
the best in usenet humor. The poster is responsible for the content. The
moderator removes duplicates, copyrighted material, posts without headers, but
does not drop articles based on content. See the group charter and FAQ for
more info. Posts: ahbou-sub@acpub.duke.edu. Mod: ahbou-mod@acpub.duke.edu.
From sht123@duke.usask.ca
Date: Fri, 21 Apr 1995 09:30:13 -0600 (CST)
From: "Shane H. W. Travis"
To: sht123@cs.usask.ca
Subject: best.sig
---
Newsgroups: rec.puzzles
From: hoey@aic.nrl.navy.mil (Dan Hoey)
Date: 1995/05/12
Subject: Re: integral pythagorean theorem puzzle...
> Aaron Koller <15821...@msu.edu> wrote:
> > a,b, and c are positive integers greater than 2. What is the
> > GREATEST value for b (in terms of a) such that a^2+b^2=c^2?
Does this really need a spoiler warning?
We have a^2=c^2-b^2; since the difference between adjacent squares
increases with b (and the distance between nonadjacent squares
increases faster) the best we can do is c=b+1.
a^2=(b+1)^2-b^2=2b+1, so b=(a^2-1)/2. Clearly this is an integer if
and only if a is odd.
If a is even, then, we can do no better than c=b+2. Then
a^2=(b+2)^2-b^2=4b+4, so b=a^2/4 - 1, which is an integer.
Dan
Hoey@AIC.NRL.Navy.Mil
---
Article 28466 of rec.puzzles:
From: hoey@aic.nrl.navy.mil (Dan Hoey)
Newsgroups: rec.puzzles
Subject: Re: More Number Puzzlers [ spoiler ]
Supersedes:
Date: 15 May 1995 22:10:33 GMT
Organization: Navy Center for Artificial Intelligence
In-reply-to: spurdy@pomona.edu's message of 13 May 95 11:00:35 PDT
spurdy@pomona.edu writes:
> Find a number whose digits when taken as a string of one digit
> numbers will represent the powers of the prime factorization of the
> original number. The factorization must be listed in order,
> including every prime for which there is a digit.
> As this is poorly phrased, I will demonstrate a close answer.
> If I were allowed to begin at the ones digit and progress backward,
> 12 would be correct, as it is 3^1 * 2^2.
So, when you say "in order", you mean in big-endian order. The
example with 12 is also "in order"--it's just in little-endian order.
This notice has been brought to you by the truth-in-endianism
guild.
Spoiler:
^L
According to computer search, the first one is 81312000.
There are no others up to 10^19.
There are also no little-endian solutions between 13 and 10^19.
This is an excellent exercise in finding ways to speed up an algorithm
that's running just a tad too slow....
Dan
Hoey@AIC.NRL.Navy.Mil
---
Newsgroups: sci.math
From: hoey@aic.nrl.navy.mil (Dan Hoey)
Date: 1995/05/18
Subject: Re: Multiperfect Numbers
hartley@madvax (Michael Hartley) writes:
> So "perfect" numbers (such as 6 and 28) are 2-perfect.
Too, too perfect. In Guy's book, the terminology is "2-fold perfect".
> While on this topic, are there any odd k-perfect numbers, for any k?
Only one is known.
Dan
Hoey@AIC.NRL.Navy.Mil
---
Article 13456 of rec.arts.sf.fandom:
From: hoey@aic.nrl.navy.mil (Dan Hoey)
Newsgroups: alt.fandom.cons,rec.arts.sf.fandom
Subject: Disclave Hotel Rooms -- last chance, act NOW
Followup-To: alt.fandom.cons
Date: 18 May 1995 13:48:18 GMT
Organization: Navy Center for Artificial Intelligence
There is bad news and good news.
All rooms at the Renaissance Washington Hotel have been reserved for
Friday and Saturday nights of Disclave '95 (26 and 27 May). That's
bad news if you don't have your Disclave room yet.
The good news is that the committee has temporarily reserved rooms for
the party floor, and about 30 of these rooms are still available. We
blocked that floor separately to avoid noise complaints. You don't
have to hold a party--all we ask is that you abide the noise of the
other parties. Parties will shut down by 2:00 AM each night.
The bad news is that committee will lose these rooms if we don't have
people to reserve them by Friday, 19 May. That's tomorrow. So you
have to act quickly if you want to get one of those party rooms.
Call Kitty Jensen at 703-644-0697. Act now, her answering machine is
standing by.
Dan Hoey Hoey@AIC.NRL.Navy.Mil
Chair, Disclave '95
---
From hoey@AIC.NRL.Navy.Mil Fri May 19 12:25:03 1995
Date: Fri, 19 May 95 12:24:21 EDT
From: hoey@AIC.NRL.Navy.Mil
To: "Keith F. Lynch"
Subject: Re: More Number Puzzlers
Cc: mlorton@eshop.com, spurdy@pomona.edu
Status: RO
I hope you all find this interesting, I've just copied addresses
from KFL's message.
> Dan Hoey says he took it to 19 digits and found no solutions other than
> mine, and "12" for the other direction.
Eventually, I got it up to 10^22 digits (both ways). Still no more
solutions. I wonder if there's any decent way of estimating the
probability of there being any more. I wouldn't be surprised if it
turns out to be small, like with Fermat primes.
The first thing was:
================
(defun findsfn (primes start end &optional (rad 10))
(labels ((findsfn1 (rprimes num nrad)
(cond ((>= num end))
(rprimes
(setq nrad (* nrad rad))
(dotimes (e rad)
(findsfn1 (cdr rprimes) num nrad)
(setq num (* num (car rprimes)))
(incf nrad)))
((< num start))
((= nrad num) (print num)))))
(findsfn1 primes 1 0)))
================
Called with (findsfn (firstnprimes nd) (expt 10 (1- nd)) (expt 10 nd))
to find the nd-digit solutions. (sfn stands for self-factoring number).
Which is essentially what you're doing, except that I had the cutoff
for getting too large. And I called it separately for each number of
digits, rather than figuring out where the decimal point goes "on the
fly". Also, instead of checking the digits at the end, I built up the
number using the digits as I generated them, and checked for equality
at the end.
This only got me up to 10^16 or so, then I thought of a faster version:
================
(defun findsfn (primes start end &optional (rad 10))
(labels ((findsfn1 (rprimes num nrad)
(cond ((>= num end))
((and rprimes
(let ((minmul (ceiling
(* nrad (expt 10
(length rprimes)))
num))
(maxmul (floor
(1- (* (1+ nrad)
(expt 10
(length rprimes))))
num)))
(when (>= minmul maxmul)
(and (= minmul maxmul)
(findsfn2 rprimes num nrad minmul))
t))))
(rprimes
(setq nrad (* nrad rad))
(dotimes (e rad)
(findsfn1 (cdr rprimes) num nrad)
(setq num (* num (car rprimes)))
(incf nrad)))
((< num start))
((= nrad num) (print num))))
(findsfn2 (rprimes num nrad mul)
(cond ((>= num end))
(rprimes
(setq nrad (* nrad rad))
(do ()
((/= 0 (mod mul (car rprimes))))
(setq num (* num (car rprimes))
nrad (1+ nrad)
mul (floor mul (car rprimes))))
(findsfn2 (cdr rprimes) num nrad mul))
((< num start))
((= nrad num) (print num)))))
(findsfn1 primes 1 0)))
================
The way this works is that after you have guessed several of the
high-order digits, they are also exponents in the factorization of a
number that will be a divisor of any sfn that has those high-order
digits. When I got to the point that there was only one ND-digit
number with those high-order digits and that divisor, I stopped
guessing.
There might be some mileage to just pruning the search instead of
waiting until search was entirely unnecessary, but I didn't figure it
out. This also has a bug--in the non-guessing stage, I might get a
digit that wants to be greater than 9. Unlikely, never happened, and
it would be easy enough to check for later.
See you at Disclave.
Dan
---
Article 7619 of alt.fandom.cons:
From: hoey@aic.nrl.navy.mil (Dan Hoey)
Newsgroups: alt.fandom.cons,rec.arts.sf.fandom
Subject: Disclave Hotel Rooms -- gone
Supersedes:
Followup-To: alt.fandom.cons
Date: 19 May 1995 21:19:22 GMT
Organization: Navy Center for Artificial Intelligence
In-reply-to: hoey@aic.nrl.navy.mil's message of 18 May 1995 13:48:18 GMT
As of 6 pm, Friday 19 May, Disclave has released its rooms at the
Renaissance Washington Hotel, and they will quickly be snapped up by
the tourists who also want to stay in Washington that weekend. So you
can try to get a room by calling the hotel (202-898-9000) but if they
tell you to call Kitty Jensen, tell them their information is out of
date. If they don't have rooms, there aren't any.
There is a Comfort Inn about four blocks away from Disclave (500 H St
NW, 202-289-5959) that I'm told was used at InterOp; you could try
them too. Be careful in Chinatown after dark, though--timid people
take a $4 cab ride.
I don't advise going to the New Carrollton Sheraton-Howard Johnson-
Sheraton (it's a Ramada now) and commuting by Metro. One, the Metro
closes at midnight, and two, that neighborhood is probably _more_
dangerous than DC.
See you at Disclave.
Dan Hoey Hoey@AIC.NRL.Navy.Mil
Chair, Disclave '95
---
Article 7647 of alt.fandom.cons:
From: hoey@aic.nrl.navy.mil (Dan Hoey)
Newsgroups: alt.fandom.cons
Subject: Disclave '95 preliminary program
Date: 22 May 1995 21:37:29 GMT
Organization: Navy Center for Artificial Intelligence
This is a preliminary copy of the Disclave '95 program. "Preliminary"
means I hope it's right but it's still subject to correction. The
serial _Zombies of the Stratosphere_ will be shown in twelve episodes
between the listed films.
Dan Hoey Hoey@AIC.NRL.Navy.Mil
Chair, Disclave '95
================================================================
Friday
5:00 PM
Program A Hard SF
C. Asaro, D. Bischoff, H. Clement, S. Lewitt, C. Sheffield (M)
6:00 PM
Program A Fannish History
D. Lynch (M), J. Mayhew, D. Smith, L. Smith, T. Veal
Program C Reading
A. Jackson
7:00 PM
Film A 40 Year Godzilla Retrospective
B. Eggleton
Program C Reading
J. Mayhew
8:00 PM
Discave Signature reception
The grand melee of autographing.
Film _Godzilla '85_
10:00 PM
Film _Bram Stoker's Dracula_
12:15 AM
Film _Roger Corman's Frankenstein Unbound_
Saturday
10:00 AM
Program A The Effect of Word Processors
R. Chase, H. Clement, M. Gear (M), J. Sherman
Program B Women in Fantasy Cultures
M. Frey, L. Gilman, C. Golden, S. Shwartz
Program C Reading
R. Miller
11:00 AM
Program A What Does an Editor Do?
S. Edelman, L. Gilman, P. Heck (M), D. Keller, J. Sherman,
D. Weinstein
Program B Astronomical Art
N. Blanchard, H. Clement, B. Eggleton, R. Miller (M)
Program C Reading
C. Sheffield
Room 9 KaffeeKlatsch
D. Bischoff, E. McFadden
12:00 PM
Program A Future Sex
C. Asaro, G. Bowen, B. Clough, S. Lewitt, M. Van Name (M),
L. Watt-Evans
Program B Collaborations
D. Bischoff (M), E. Foxxe, J. Rivkin, M. Swanwick
Program C Reading
J. Chalker
Film _5000 Fingers of Dr. T_
1:00 PM
Program A Religion in SF and Fantasy
G. Bowen, R. Chase, A. Gilliland, J. Mayhew (M)
Program B Starting a New Genre Magazine
S. Edelman (M), J. Felice, A. Kessler, W. Lapine, E. McFadden
Program C Reading
C. Asaro
Room 9 KaffeeKlatsch
J. Sherman, T. Weisskopf
2:00 PM
Program A Guest of Honor Speech
C. Sheffield
3:00 PM
Program A Fantasy in the Future
A. Gilliland, C. Golden, D. Keller (M), D. Schweitzer, S. Shwartz,
L. Watt-Evans
Program B Art or Illustration
N. Blanchard, D. Coltrain, B. Eggleton (M), K. Kofoed, R. Miller
Program C Reading
J. Sherman
Room 9 KaffeeKlatsch
H. Clement, L. Gilman
Film _Dark Crystal_
4:00 PM
Program A Ten From the Art Show
M. Gear, L. Gilman, P. Heck, J. Mayhew (M), M. Swanwick
Program B The Fanzine Panel
M. Feder, A. Gilliland, D. Keller, D. Lynch, N. Lynch (M), L. Smith
Program C Reading
D. Bischoff
Room 9 KaffeeKlatsch
E. Kotani, C. Sheffield
5:00 PM
Film Art GOH Interview
B. Eggleton, T. Schaad
Program B Care and Feeding of a Small Press
J. Chalker, D. Fratz, W. Lapine (M), E. McFadden
Program C Reading
S. Lewitt
8:00 PM
Film _The Mask_
9:00 PM
Room 9 Dance
10:00 PM
Film _The Crow_
12:00 AM
Film _The Shadow_
Sunday
10:00 AM
Program A The Place of Evil in SF
G. Bowen, M. Frey (M), S. Lewitt, S. White
Program C Reading
L. Gilman
11:00 AM
Program A As The History Turns
E. Baker, M. Feder, M. Gear, E. McFadden, A. Wheeler, S. White (M)
Program B Fantasy Research
E. Foxxe, A. Klause, J. Rivkin, J. Sherman, S. Shwartz (M)
Program C Reading
H. Clement
Room 9 KaffeeKlatsch
B. Eggleton, D. Weinstein
12:00 PM
Program A Charles Sheffield Science Talk
C. Sheffield
Program B Styles and Genre
L. Gilman, A. Klause, S. Shwartz, M. Swanwick (M), L. Watt-Evans
Program C Reading
D. Schweitzer
Film _Hoppity Goes to Town_
1:00 PM
Program A SF on TV
D. Bischoff, D. Fratz, M. Gear, L. Loban (M), D. Weinstein
Program B Is It a Book Yet?
A. Gilliland, P. Heck, S. Lewitt, R. Miller, J. Sherman (M)
Program C Reading
C. Golden
Room 9 KaffeeKlatsch
J. Chalker
1:45 PM
Film _George Pal Puppetoons_
2:00 PM
Program A I Was Only a Child at the Time But ...
D. Bischoff, H. Clement, L. Gilman, P. Heck (M)
Program B Teaching Writing
W. Lapine, J. Rivkin (M), D. Schweitzer, M. Van Name
Program C Reading
R. Chase
Room 9 KaffeeKlatsch
C. Golden, L. Watt-Evans
Film _Return to Oz_
3:00 PM
Program A What I like Least About Being a Writer
J. Chalker, M. Frey, C. Golden, A. Klause (M), J. Sherman
Program B Science and Fiction
C. Asaro, E. Kotani, C. Sheffield (M), M. Swanwick, S. White
Program C Reading
M. Swanwick
Room 9 KaffeeKlatsch
G. Bowen, A. Gilliland
4:00 PM
Program A What I like Least About Being an Artist
N. Blanchard, B. Eggleton, K. Kofoed (M), R. Miller
Program B Future Elections
A. Gilliland, J. Mayhew, P. Pavlat (M), D. Smith, T. Veal, A. Wheeler
Program C Reading
S. Shwartz
Room 9 KaffeeKlatsch
W. Lapine, R. Miller
4:00 PM
Film _The Witches_
5:00 PM
Program B The Real Alien
G. Barr (M), R. Chase, H. Clement, K. Kofoed, C. Sheffield
7:15 PM
Film _Black Moon_
9:00? PM
Room 9 Dance
Film _Prospero's Books_
12:00 AM
Film _Naked Lunch_
================================================================
---
Newsgroups: comp.ai.games
From: hoey@aic.nrl.navy.mil (Dan Hoey)
Date: 1995/05/23
Subject: Re: chomp strategy papers/discussion.
gmcde...@mlsma.mlm.att.com (Graham P. McDermott) writes:
> I've just entered a simple competition where the entrant has to
> write programs that can play chomp successfully. In the entry
> information it says that there has been some research/article
> written somewhere that looks into strategies for chomp and that
> looking there could pay off.
It seems to me that if the entry information gave the author and
title of the article, you would have posted it. And if not, it seems
the competition is to find it yourself, not to ask comp.ai.games
(nor rec.puzzles, where it's off topic). That said, I can drop a
couple of hints that are well-known to anyone who's worked on it.
> ps. Chomp is the game where you're given a random rectangular playing board
> with cookies on it. There also exists a poison cookie. You know
> where the poison one is, but don't want to eat it. You take turns
> with your opponent to bite sections out of the board. A bite
> consists of removing a small rectangular sub-section of the board.
I don't know if the entry didn't explain it, or if it's you who can't
explain it, but the above explanation fails to impart that:
-- The board is a rectangle of some arbitrary size, but it's not
"random" in any probabilistic sense.
-- The poison cookie is always at the northwest corner of the board.
-- A turn is to take a cookie and everything to the south and/or east
of it. Except for the first move, this need not be a rectangle.
As for a hint, consider that if we call the poison cookie (0,0), then
it has two neighbors (1,0) and (0,1). Whoever first takes a neighbor
loses, because a good opponent will take the other neighbor. Now
generalize.
There's also an easy proof that the first player wins on any
rectangular board larger than 1x1. But it doesn't help you play.
Three-dimensional infinite chomp is also an important game, which
David Gale formalizes as:
> In the game of chomp, players alternate stating triples of non-negative
> integers, and once a triple (a,b,c) is named, then for ever after
> neither player can name a triple (d,e,f) with d>=a, e>=b, and f>=c. A
> player who names (0,0,0) loses. Does the first or second player have a
> winning strategy?
As of 1992, he offered a reward of $200 for the solution.
Dan Hoey
Hoey@AIC.NRL.Navy.Mil
---
Date: Tue, 23 May 95 13:11:27 -0400 (EDT)
From: Dan Hoey
To: Cube Lovers
Subject: M-conjugacy vs. C-Conjugacy in the Slice group
Jerry Bryan tried to communicate about this to cube-lovers, but
there's apparently a technical difficulty.
On 20 May, Jerry said:
I doubt that Mark's theory about GAP using C-conjugacy for slice
instead of M-conjugacy is correct. I already have 50 positions
to 23 for GAP, and using C-conjugacy would just make my results
larger. For example, RL' and R'L are M-conjugate positions,
but not C-conjugate positions.
I emailed him to note to the contrary that RL' and R'L are indeed
C-conjugates, for example under 180 degree rotation around the F-B
axis. I did wonder, though, whether that meant that there could be
C-conjugate slice positions that were not M-conjugate.
He emailed me:
We can observe that R and R' are not C-conjugates, nor are L' and L,
which suckered me into stating that RL' and R'L are not. But
rewrite R'L as LR' since opposite face moves commute. Now, RL'
and LR' are clearly C-conjugate.
In fact, I have now verified with a quick search program that
all M-conjugates in the slice group are also C-conjugates. Hence,
there are 50 C-conjugate classes in slice, just as there are
50 M-conjugate classes.
In retrospect, I don't think the search program was necessary....
and continues with an argument that did not convince me, but the
following does:
First, consider the central inversion v, which maps each point of the
cube to its diametric opposite. Conjugation by v maps each face-turn
(e.g. F) with its diametric opposite in opposite sense (B'). Since
these are the pairs that constitute a slice move, and they commute, we
have:
v' FB' v = (v' F v) (v' B' v) = B' F = F B',
and similarly for the other slice moves, showing that each slice move
is its own v-conjugate. This extends to a proof that each position in
the slice group is its own v-conjugate:
v' s1 s2 ... sn v = (v' s1 v) (v' s2 v) ... (v' sn v)
= s1 s2 ... sn.
Suppose that we have two M-conjugate positions X, Y in the slice
group. So X = m' Y m for some m in M. If m is in C, then X and Y are
C-conjugate and we are done. Otherwise take the central inversion v;
we know that mv is in C. We also know that
X = v' X v = v' m' Y m v = (mv)' Y (mv).
So X and Y are C-conjugate in this case as well. QED.
Note: "Being its own v-conjugate" might as well be called "being
v-symmetric".
Dan
Hoey@AIC.NRL.Navy.Mil
---
Newsgroups: sci.math
From: hoey@aic.nrl.navy.mil (Dan Hoey)
Date: 1995/05/24
Subject: Re: pleas ehelp with this "simple" puzzle
u9014...@muss.cis.McMaster.CA (M.S. Chan) writes:
> If you are using sort by comparsion, then the minimum number of
> comparsion required - no matter how smart the algorithm is - is O(n log
> n), where log is log to the base 2.
He wasn't counting comparisons. He was counting "moves", in which a
move is the reversal of some initial segment of the sequence. Your
upper bound is not accurate for this measure.
Dan Hoey
Hoey@AIC.NRL.Navy.Mil
---
Newsgroups: rec.arts.sf.announce
From: hoey@aic.nrl.navy.mil (Dan Hoey)
Date: 1995/05/24
Subject: Disclave '95 preliminary program
This is a preliminary copy of the Disclave '95 program. "Preliminary"
means I hope it's right but it's still subject to correction. The
serial _Zombies of the Stratosphere_ will be shown in twelve episodes
between the listed films.
Dan Hoey Hoey@AIC.NRL.Navy.Mil
Chair, Disclave '95
================================================================
Friday, 26 May 95
5:00 PM
Program A Hard SF
C. Asaro, D. Bischoff, H. Clement, S. Lewitt, C. Sheffield (M)
6:00 PM
Program A Fannish History
D. Lynch (M), J. Mayhew, D. Smith, L. Smith, T. Veal
Program C Reading
A. Jackson
7:00 PM
Film A 40 Year Godzilla Retrospective
B. Eggleton
Program C Reading
J. Mayhew
8:00 PM
Discave Signature reception
The grand melee of autographing.
Film _Godzilla '85_
10:00 PM
Film _Bram Stoker's Dracula_
12:15 AM
Film _Roger Corman's Frankenstein Unbound_
Saturday, 27 May 95
10:00 AM
Program A The Effect of Word Processors
R. Chase, H. Clement, M. Gear (M), J. Sherman
Program B Women in Fantasy Cultures
M. Frey, L. Gilman, C. Golden, S. Shwartz
Program C Reading
R. Miller
11:00 AM
Program A What Does an Editor Do?
S. Edelman, L. Gilman, P. Heck (M), D. Keller, J. Sherman,
D. Weinstein
Program B Astronomical Art
N. Blanchard, H. Clement, B. Eggleton, R. Miller (M)
Program C Reading
C. Sheffield
Room 9 KaffeeKlatsch
D. Bischoff, E. McFadden
12:00 PM
Program A Future Sex
C. Asaro, G. Bowen, B. Clough, S. Lewitt, M. Van Name (M),
L. Watt-Evans
Program B Collaborations
D. Bischoff (M), E. Foxxe, J. Rivkin, M. Swanwick
Program C Reading
J. Chalker
Film _5000 Fingers of Dr. T_
1:00 PM
Program A Religion in SF and Fantasy
G. Bowen, R. Chase, A. Gilliland, J. Mayhew (M)
Program B Starting a New Genre Magazine
S. Edelman (M), J. Felice, A. Kessler, W. Lapine, E. McFadden
Program C Reading
C. Asaro
Room 9 KaffeeKlatsch
J. Sherman, T. Weisskopf
2:00 PM
Program A Guest of Honor Speech
C. Sheffield
3:00 PM
Program A Fantasy in the Future
A. Gilliland, C. Golden, D. Keller (M), D. Schweitzer, S. Shwartz,
L. Watt-Evans
Program B Art or Illustration
N. Blanchard, D. Coltrain, B. Eggleton (M), K. Kofoed, R. Miller
Program C Reading
J. Sherman
Room 9 KaffeeKlatsch
H. Clement, L. Gilman
Film _Dark Crystal_
4:00 PM
Program A Ten From the Art Show
M. Gear, L. Gilman, P. Heck, J. Mayhew (M), M. Swanwick
Program B The Fanzine Panel
M. Feder, A. Gilliland, D. Keller, D. Lynch, N. Lynch (M), L. Smith
Program C Reading
D. Bischoff
Room 9 KaffeeKlatsch
E. Kotani, C. Sheffield
5:00 PM
Film Art GOH Interview
B. Eggleton, T. Schaad
Program B Care and Feeding of a Small Press
J. Chalker, D. Fratz, W. Lapine (M), E. McFadden
Program C Reading
S. Lewitt
8:00 PM
Film _The Mask_
9:00 PM
Room 9 Dance
10:00 PM
Film _The Crow_
12:00 AM
Film _The Shadow_
Sunday, 28 May
10:00 AM
Program A The Place of Evil in SF
G. Bowen, M. Frey (M), S. Lewitt, S. White
Program C Reading
L. Gilman
11:00 AM
Program A As The History Turns
E. Baker, M. Feder, M. Gear, E. McFadden, A. Wheeler, S. White (M)
Program B Fantasy Research
E. Foxxe, A. Klause, J. Rivkin, J. Sherman, S. Shwartz (M)
Program C Reading
H. Clement
Room 9 KaffeeKlatsch
B. Eggleton, D. Weinstein
12:00 PM
Program A Charles Sheffield Science Talk
C. Sheffield
Program B Styles and Genre
L. Gilman, A. Klause, S. Shwartz, M. Swanwick (M), L. Watt-Evans
Program C Reading
D. Schweitzer
Film _Hoppity Goes to Town_
1:00 PM
Program A SF on TV
D. Bischoff, D. Fratz, M. Gear, L. Loban (M), D. Weinstein
Program B Is It a Book Yet?
A. Gilliland, P. Heck, S. Lewitt, R. Miller, J. Sherman (M)
Program C Reading
C. Golden
Room 9 KaffeeKlatsch
J. Chalker
1:45 PM
Film _George Pal Puppetoons_
2:00 PM
Program A I Was Only a Child at the Time But ...
D. Bischoff, H. Clement, L. Gilman, P. Heck (M)
Program B Teaching Writing
W. Lapine, J. Rivkin (M), D. Schweitzer, M. Van Name
Program C Reading
R. Chase
Room 9 KaffeeKlatsch
C. Golden, L. Watt-Evans
Film _Return to Oz_
3:00 PM
Program A What I like Least About Being a Writer
J. Chalker, M. Frey, C. Golden, A. Klause (M), J. Sherman
Program B Science and Fiction
C. Asaro, E. Kotani, C. Sheffield (M), M. Swanwick, S. White
Program C Reading
M. Swanwick
Room 9 KaffeeKlatsch
G. Bowen, A. Gilliland
4:00 PM
Program A What I like Least About Being an Artist
N. Blanchard, B. Eggleton, K. Kofoed (M), R. Miller
Program B Future Elections
A. Gilliland, J. Mayhew, P. Pavlat (M), D. Smith, T. Veal, A. Wheeler
Program C Reading
S. Shwartz
Room 9 KaffeeKlatsch
W. Lapine, R. Miller
Film _The Witches_
5:00 PM
Program B The Real Alien
G. Barr (M), R. Chase, H. Clement, K. Kofoed, C. Sheffield
7:15 PM
Film _Black Moon_
9:00? PM
Room 9 Dance
Film _Prospero's Books_
12:00 AM
Film _Naked Lunch_
Sunday, 29 May
No panels,
Film reruns by popular acclaim
================================================================
---
Newsgroups: rec.arts.sf.fandom, alt.fandom.cons
From: hoey@pooh.tec.army.mil (Dan Hoey)
Date: 1995/05/31
Subject: Re: Convention Beginner's Guide on Sale
politico@io.com spews:
a noisome little puddle that pretty well confirms my first impression
of his experience, maturity, and attitude. But one chunk floats up
from the rest:
> ... got a glowing review from Richard Preston, a retired engineer
> from NASA's Launch Vehicles Division and a long time friend of the
> convention as well as a regular guest.
So, are there other people out there who, like politico and I, have
had their ego stroked by Dick Preston? And is there anyone besides
politico who found it a meaningful experience? Don't get me wrong--
Dick's a nice guy and a friend of mine. But his habitual sycophancy
is so extreme that I need to keep reminding myself it's not meant as
some obscure form of sarcasm.
Dan
Hoey@AIC.NRL.Navy.Mil
---
Article 14384 of rec.arts.sf.fandom:
From: hoey@aic.nrl.navy.mil (Dan Hoey)
Newsgroups: rec.arts.sf.fandom
Subject: Re: 1995 DISCLAVE
Date: 06 Jun 1995 03:29:20 GMT
Organization: Navy Center for Artificial Intelligence
In-reply-to: avedon@cix.compulink.co.uk's message of Mon, 5 Jun 1995 06:54:58 GMT
avedon@cix.compulink.co.uk (Rob Hansen) writes:
> There was general asgreement among the people I hung out with that was
> the best DISCLAVE in ages, and it was certainly the best of the four I've
> attended....
Well, I'm very glad to hear that, especially if I may presume that one
of those hangers-out-with is Avedon. I heard it when she decried
Disclave for not being what it used to be, but I never got up the
nerve to ask if there were any of the differences that I could work to
ameliorate. I've heard a few tales of the glorious Disclaves of yore,
but I didn't involved until the mid-'80s, so all the ones I've seen
are but pitiful echoes &c.
> Mindful of the complaints in rasff about the vandalism
> allegedly caused by the Goths, I kept an eye out but saw nothing
> untoward.
I don't know how to identify vandals by looking at how they dress.
The only criterion I know how to apply to tell whether we are being
invaded by barbarians is to check on how many of the attendees lack
name tags. I think it was way down. The best explanation I've heard
is that a lot of crashers were tossed out on the street at Balticon,
the previous month. That, and the fact that hotel security nabbed a
half-dozen on the way in and turned them around. Our hotel security
was excellent this year, both in stopping what could be problems and
in not bothering with what wasn't. So pleasant after the GM-from-hell
we had at the Sheraton.
I'm also glad we have the rock garden. It's not much of an
accomodation for the people who want to stay up all night, but it's at
least someplace. I wish we had something better, but we're really
pretty boxed in, since the hotel wants to clean up its lobby for the
morning, and is not interested in filling the function floors with
bored fen. For social groups of ten or fewer, it's possible to hang
out in a sleeping room, but I don't really know where to put larger
groups. Possibly we can work to make the rock garden a little less
stark. Covert's thinking of finding chairs.
At any rate, the hotel is happy with us, and we are happy with the
hotel and the world. We had about 800 attendees this year, which is
close to last year's figure. With next year at the same hotel, we may
see a small increase. Maybe next year they will get rooms before the
block expires. (ha!)
Dan Hoey Chair, Disclave '95
Hoey@AIC.NRL.Navy.Mil
---
Newsgroups: news.groups, rec.games.go, rec.games.abstract
Followup-To: news.groups
From: hoey@aic.nrl.navy.mil (Dan Hoey)
Date: 1995/06/07
Subject: Split yes! Rename no! Please keep rec.games.go
Ken Warkentyne writes:
> Rename rec.games.go -> rec.games.go.misc
> The renaming of the base group follows modern usenet convention.
> It does not indicate the relative importance of the various groups;
> it only servers as a marker that more specialized groups do exist.
> The charter will remain as it is, with the exception that postings
> more relevant to subgroups should now be posted there, rather than
> to the main group.
If the charter is to remain the same, there is no call to rename the
group form "rec.games.go" to "rec.games.go.misc". It causes needless
disruption to do so, and the longer name is just a little more
cumbersome. You should keep rec.games.go, and just add subgroups.
That has worked fine for sci.math and rec.puzzles, and it would work
fine for rec.games.go.
The only reason the addition of ".misc" seems to be a "modern
convention" is that some of the volunteer advisors on the newsgroup
creation list ask for it to be added whenever someone proposes a group
split, and the proposer usually goes along. Now that they have gotten
a number of them to go along, they call it a "standard" and try to get
everyone to go along with it.
The "technical" reasons, when you ask for them, turn out to be a lot
of "we think it is better that way" and "some software doesn't deal
with the other way well". The first is not a technical reason, it's
just an opinion. The second is a poor excuse for broken software--
they ought to just fix the software, instead of trying to change all
the newsgroups.
I think it's a bad idea, and people should oppose it to prevent it
from becoming even more entrenched than it already is.
Dan Hoey
Hoey@AIC.NRL.Navy.Mil
---
Newsgroups: rec.arts.sf.written
From: hoey@aic.nrl.navy.mil (Dan Hoey)
Date: 1995/06/09
Subject: Re: H. Ellison online chat: help me pose TLDV question!
Geoffrey A. Landis writes:
> Ian McDowell, ikmcd...@hamlet.uncg.edu writes:
> > Finally, I don't know what kind of contract Harlan's authors
> > signed, but at this late date I can't imagine them being able to
> > pull their stories (and sell them elsewhere) if they so desire.
> > Any word on this ?
> I have heard of at least two authors who have pulled their TLDV stories
> and published them elsewhere.
There are letters from Ellison in The Last Deadloss Visions/Book on
the Edge of Forever admitting the authors' rights to take back their
stories (and begging them not to do so). From his 14 December 1977 to
all contributors:
"It is incumbent on me to advise you once again that the stories
have, in fact, reverted to you. Long since. You can refuse to
sign, keep the advance payment you received, and sell the story
elsewhere. Or you can trust me just one more time and stay with
the project."
I'm not sure if he's added any more contributors since then, and if so
what their status is.
Dan
Hoey@AIC.NRL.Navy.Mil
---
Newsgroups: rec.arts.sf.written
From: hoey@aic.nrl.navy.mil (Dan Hoey)
Date: 1995/06/09
Subject: Re: Harlan Ellison's Xenogenesis
da...@NetVision.net.il (Lisa Aaronson) writes:
> I've seen mentions of an article by Harlan Ellison called
> Xenogenesis. I'd like to read it, but no one seems to know where
> it can be found. Was it one of the things that he published in a
> special limited edition or something?
"Xenogenesis" appeared in the August, 1990 issue of _Isaac Asimov's
Science Fiction Magazine_ the cover has an elephant with pink
membranes. The essay consists mostly of his October, 1984 GoH speech
at Westercon 37. It is a collection of stories of the ways that fans
have mistreated SF professionals, mostly reponses to his solicitation
of such stories and his personal experiences.
Like a lot of Ellison, it teeters on the edge between aggrieved
complaints against people who have victimized him and mean-spirited
vindictiveness toward people who have not shown him the respect he
considers appropriate. There was a lot of discussion of it in
sf-lovers, starting in about June, 1990; perhaps you can get it from
the archives.
Dan
Hoey@AIC.NRL.Navy.Mil
---
Newsgroups: rec.arts.sf.written
From: hoey@aic.nrl.navy.mil (Dan Hoey)
Date: 1995/06/13
Subject: Re: _Gauntlet_ article on Ellison (Was Re: Ellison apology to CJ)
With regard to the _Gauntlet_'s report that Ellison's appearance at
the Philadelphia Comicfest was not a lecture but a question-and-answer
session, c...@panix.com (Charles Platt) writes:
> This is untrue. It is one of many Ellisonian rewrites of reality,
> and I'm disappointed, but not surprised, that it has been presented
> as fact in Gauntlet magazine.
The relevant section of Cusick's _Gauntlet_ article is:
The [_Journal_'s] implication that Ellison eagerly volunteered
these stories is obvious and incorrect. A videotape of the event
clearly shows Ellison taking suggestions from the audience.
During a lull in the action, between anecdotes, a member of the
audience throws out a request:
``Tell the Charles Platt story!''
``Jesus! God!'' groaned Ellison. ``Tell the Charles Platt
story! You know the Charles Platt story?!''
``No! No!'' The words rose from the crowd.
Ellison mimicked an old Jewish man: ``Tell the Charles Platt
story!'' and then in a normal voice said, ``There was this guy...
There was this guy named Charles Platt...'' [p. 111]
I didn't notice Cusick claiming to have personally listened to that
videotape, though.
> Ellison originally accused Gary Groth of PLANTING someone in the audience
> to ask questions which would "trick" Ellison into making statements that
> would get him into trouble. (Talk about conspiracy theories! The lengths
> to which Ellison will go, to make himself look like an innocent victim and
> evade responsibility for his outbursts, are really amazing.)
Well, Groth sold a lot of _Comics Journal_s on this story and its
sequelae. It is not inconceivable that he would try to raise its
juiciness level, especially if he considers that Ellison's rudeness is
something that should be better publicized. Though Cusick quotes
Groth's denial of having sponsored a shill.
> It so happens I have a tape of his rant at the comics convention. There
> was some to-and-fro between Ellison and the audience, but no more than
> usual. It is *not* possible to hear anyone saying my name, other than
> Ellison himself, who says, "You've heard the Charles Platt story, haven't
> you?" And when he gets a few "no" responses, he launches in with gusto.
Could it be that there is more than one tape, and that the audience
prompt is audible on some tapes but not others? Can you supply the
precise text of the above exchange from your tape?
> To suggest that Ellison needs to be provoked into maligning people
> is absurd....
That was not my contention. The question is whether he needs to be
prompted to speak on subjects he has pledged to remain silent about.
> The obvious question is ... why would he ask the audience if they
> have heard "the Platt anecdote" as if it's already well-known?
The rhetorical nature of the question is plausible in the _Gauntlet_'s
version.
> Evidently because it *is* a known anecdote. Since no one else has
> been telling it, one can only conclude that Ellison himself has been
> telling it....
I don't know that no one else has been telling the story. It may well
have been repeated by other witnesses, or anyone who heard the story
before the April, 1988 pledge. So the conclusion does not follow
from it being a known anecdote. It does, of course, follow from the
reports you claim to have heard of him using it ``as a staple of his
public repertoire.''
Dan Hoey
Hoey@AIC.NRL.Navy.Mil
---
Article 7963 of alt.fandom.cons:
From: hoey@aic.nrl.navy.mil (Dan Hoey)
Newsgroups: alt.fandom.cons
Subject: Re: Disclave '95 Debriefing
Date: 13 Jun 1995 16:17:33 GMT
Organization: Navy Center for Artificial Intelligence
In-reply-to: MANDRO@delphi.com's message of 13 Jun 1995 04:22:48 GMT
MANDRO@delphi.com writes:
>> We are seeking additional comments about Disclave '95. I will be
>> the Chair for Disclave '97 and I will pass along comments to next
>> year's Chair, Bob MacIntosh.
> Well, This curfew of theirs has to go... I dont know if it was
> Disclaves idea or the hotels but it was rather ridiculus...
[ellipses his]
Well, I'm not sure what you mean by "has to go", but it is virtually
certain that it will be impossible to congregate in any public area of
the hotel all night, at least next year. The alternatives I know of
are to gather in a sleeping room (quietly enough not to disturb the
neighbors) or to go outside.
It was very difficult finding a hotel at all this year, and we were
extremely fortunate that the one we found has a mellow security force.
If clearing the public areas of the hotel between 3:30 and 6 helps
them stay mellow, it does not seem ridiculous to me.
Dan Hoey Hoey@AIC.NRL.Navy.Mil
Chair, Disclave '95
---
Newsgroups: rec.arts.sf.written
Followup-To: poster
From: hoey@aic.nrl.navy.mil (Dan Hoey)
Date: 1995/06/14
Subject: Re: Ellison apology to CJ
c...@ai.mit.edu (Christian Longshore Claiborn) writes:
> c...@panix.com (Charles Platt) writes:
> [Stuff about how Harlan is a weenorhead]
That's hardly a fair or accurate summary of the message you were
responding to. Rather the message contained stuff about how Ellison
(1) mailed a dead and decaying gopher to an [unnamed] editor, (2)
delivered a veiled death threat to Platt and others, and (3) invited
himself to a story meeting to sabotage John Shirley's livelihood. I
think these instances go beyond the normal run of abrasiveness we
expect from controversial authors, regardless of the shape of their
head.
> ... While I understand that your personal issues with Ellison date back
> years and years, would it be possible for us not to pursue it further
> in this group? It really isn't about his work, it's about him
> personally, and wading through an ever-expanding morass of threads
> about how Harlan was nice to someone but mean to someone else probably
> isn't of interest to a lot of people reading this.
Well, Charles Platt was responding to someone else's direct question
about "an issue with Ellison", so perhaps your remarks should be
addressed to those of us who are asking questions on the subject. I
am quite interested in these remarks, because they have a bearing on
how much we should believe Ellison's promises to eventually deliver
_The Last Dangerous Visions_, and how much we should believe the
stories of wrongdoing and abuse that give _The Book on The Edge of
Forever_ its whistle-blowing and/or rumor-mongering flavor, and even
how much credit we should give to the accounts in "Xenogenesis". All
of these seem to be well within the charter of rec.arts.sf.written,
which is why I have been asking them here. And I very much appreciate
Charles's willingness to answer them.
As I speak only for the relatively noisy minority (of one), comments
about the appropriateness of this discussion might better be directed
to me in e-mail.
Dan Hoey
Hoey@AIC.NRL.Navy.Mil
---
Newsgroups: rec.arts.sf.written
From: hoey@pooh.tec.army.mil (Dan Hoey)
Date: 1995/06/16
Subject: Re: Harlan Ellison's Xenogenesis
Eric Oppen (cc...@cleveland.Freenet.Edu) wrote:
: As far as I can recall, it was an article he wrote that came out
: more than five years ago in _Isaac Asimov's SF Magazine._
August, 1990, actually. (No, not 1989). It's mostly from his July,
1984 Guest of Honor speech to Westercon.
: The whole thing was about
: what assholes and sociopaths a small percentage of fans were, with horror
: stories from him as well as other authors he had written to.
: The title, "Xenogenesis" referred to the benign nature of ALMOST ALL fen,
: who manage somehow to produce this group of cretins who do not resemble
: them at all.
Sadly, I believe you got the point I wish he had made, rather than the
point he really did make. He ended his speech:
[ Stuff about someone printing T-shirts that say "50 SHORT
YEARS OF HARLAN ELLISON" without offering him a royalty. ]
[ Observing that it mocks his height, and people wearing it
around him ], and not one of you thinks the subject of the T-shirt
might be hurt by such an insensitive act. One _must_ assume none
of you gave it a consideration, because the alternative is the
contemplation of someone who throws warm vomit.
And the subject of the T-shirt's logo only smiles as he signs
your autograph, appearing properly slavishly grateful for your
attention, and the fifty-year-old man says nothing.
But like George Alec Effinger and Steven King and David
Gerrold and Tim Kirk and many, many others who asked that their
names not be mentioned . . . the short fifty-year-old man will
resist more and more ever going among such people.
Because they are not kind. And one need not put up with
unkindness from those who pretend to be all of the same family of
noble dreamers, not when there are so many total strangers in the
world who will be beastly without reason.
Children of our dreams, so many of you have said. Oh, how I
was moved by what you wrote; oh, how you turned my life around;
oh, how much this or that story meant to me when I was lonely and
desperate. Children of our dreams.
Xenogenesis.
The children do not resemble the parents.
And many of you wonder why some of those literary parents
think positively of the concept that birth control might be made
retroactive.
So I think he's complaining that the "noble dreamers" who _write_ SF
have attracted fandom, which he finds predominantly rude and boorish.
I had more sympathy for this before I heard the tidbit that until he
sprung this on the audience at the end of a long speech about vomit-
throwers, he never said one word about disliking the shirt. It's
reported he'd even complimented someone wearing it, saying it was
a cute gag. Then he suddenly calls them insensitive xenogenes, in
public, while they were wearing the shirts, just to make a point.
If that isn't insensitive abuse, I don't know what is.
I might remark on how the general adulation of mostly good-hearted fen
has inadvertently fed the malignant ego of a writer who delights in
turning their admiration to insults, and their good humor to
embarrassment. Now that's xenogenesis.
I'm tempted to see if I can get a shirt printed that says "61 YEARS OF
PETTY VINDICTIVENESS" and wear it to the NASFiC.
Dan Hoey
Hoey@AIC.NRL.Navy.Mil
---
Article 14976 of rec.arts.sf.fandom:
From: hoey@pooh.tec.army.mil (Dan Hoey)
Newsgroups: rec.arts.sf.fandom
Subject: Re: 1995 DISCLAVE
Date: 20 Jun 1995 16:36:17 GMT
Organization: Naval Research Laboratory, Washington, DC
Avedon Carol (avedon@cix.compulink.co.uk) wrote:
: ... The a.s.b. party wasn't exactly "open" - you had to sign a
: release to get in, for one thing, and pass through a couple of
: layers of internal security. They certainly weren't letting kids
: wander in there.
There was a certain amount of congregating in the hallway outside the
ASB rooms, though. I didn't notice anything untoward there, but the
hotel is a little nervous about it--apparently the Tailhook affair set
a precedent that hotels have liability for sexual misconduct in the
halls.
: If you are going to get into a panic because you see someone walking
: through a hallway in a short black leather dress, well, I'd prefer
: you stay at the church social where you belong and not come to sf
: cons...
Though if the someone in the short black leather dress is leading
someone else by a chain, and the someone else is wearing a leather
suit and manacles and studded leather collar, it starts looking a
little less like escaping _to_ a church social than escaping _from_
someone's private bondage scene. I didn't try to stop it--mainly
because I don't think the people who would really mind it recognize
the B&D overtones--but I was not comfortable with the situation. I
don't want to get in the business of defining a Disclave dress code,
but if it freaks the mundanes we may need to do something.
Dan Hoey Hoey@AIC.NRL.Navy.Mil
Chair, Disclave '95
---
Newsgroups: sci.stat.edu, rec.puzzles
From: hoey@pooh.tec.army.mil (Dan Hoey)
Date: 1995/06/21
Subject: Re: Washington Post on Statistics in Elementary School
Howard Leathers (HowardL@arec.umd.edu) wrote:
: Q. Imagine a disease that is found in 0.1% of the population, or one in
: every 1000 people. The test to see whether somebody has the illnes is
: 98% accurate. In other words, 2% of the people who test positive do not
: have the disease, and 2% of the people who test negative do have it.
: o What portion of people who test postive for the disease
: actually have it?
According to the problem statement, "2% of the people who test
positive do not have the disease", so 98% do. Amazingly enough,
that's the answer they get. The general incidence of the disease is a
red herring, except that ...
Any test that _has_ an accuracy of the type defined (i.e., whose ratio
of true positives to total positives is equal to its ratio of true
negatives to total negatives) must have an failure rate of at most the
disease incidence (and, for pandemics, at most the disease
non-incidence). So the problem statement is self-contradictory.
: Tuesday's paper carried a correction of the definition of what it means
: for the test to be 98% accurate.
And what was that definition? That 98% of the answers are correct?
If so, that leads us to a range of answers. The rate Fn of false
negatives cannot exceed the incidence rate, so will be between 0 and
.1%. Given that the failure rate is 2%, the rate Fp of false
positives is (2% - Fn), between 1.9% and 2%. The rate of positive
tests is (.1% - Fn + Fp) = (2.1% - 2 Fn), among which (.1% - Fn) are
correct. The ratio requested can range from .1/2.1 ~ 4.76% (no false
negatives) to 0% (if all the positives are false negatives). That
last number is somewhat bogus, though--it requires a test that gives
positive indications only on the uninfected! If we require the test
to be _indicative_, such that infected subjects are at least as likely
as the noninfected to test positive, then the minimum accuracy rate on
positive tests is 49/1048 ~ 4.68%.
This still looks a little difficult for "... a problem that the
National Council of Teachers of Mathematics hopes middle school
students wold be able to answer," unless they're talking about
about 0.1% of the middle school students. I wonder what the failure
rate on this problem would be.
Dan
Hoey@AIC.NRL.Navy.Mil
---
Date: Thu, 22 Jun 95 03:43:59 -0400 (EDT)
From: Dan Hoey
To: Cube Lovers
Subject: Ways to Calculate the Real Size of Cube Space?
Martin Schoenert says:
> I can't figure out how the brute force computer search works.
and while Jerry Bryan gives one answer, I have another. For you see,
I also ran a brute force computer search for the symmetry classes,
too. And while it agrees with Jerry's answers, mine was a significantly
different algorithm, which I discuss a little a the end of this message.
It appears to me that Dan and Jim Saxe must have realized all the
important pieces for your new method when they wrote their seminal
``Symmetry and Local Maxima (long message)'' message of 1980/12/14.
As Jerry points out, they did calculate the important values for
9 of the 33 conjugacy classes of subgroups of M (those whose sizes
are a multiple of 12). It is neither clear from their message how
they found those 9 classes (in fact they apparently found all 98
subgroups of M), nor how they computed the numbers of elements of
G that have a specific subgroup of M as symmetry group.
Perhaps Dan can say a little bit more about this?
First, to find all the subgoups of M. I represented the elements of
M as a list of permutations on faces, found easily enough by finding
the closure of the generators. Then I did a depth-first search for
subgroups, branching by computing the closure of the current subgroup
with each possible element not in that subgroup, and cutting off the
search on previously-seen subgroups. It's quick, it's dirty, it
works. I found the nine subgroups of order a multiple of 12, as shown
in the Hasse subgroup diagram:
order 48 . . . M_
/|\\_
/ | \ \_
/ | \ \_
order 24 . A . H . C \_
\ | / \_
\ | / \_
\|/ \
order 12 . . . E . . . . .T[1..4]
(except we called E "AC" back then). The trick then was to find
all the E-symmetric positions and all the T1-symmetric positions;
the tasks of finding the full symmetry group of such positions and
counting the positions for T2, T3, and T4 were straightforward.
The best tool we had for figuring out symmetric positions was
essentially the one I wrote about in ``The real size of cube space''
on 4 Nov 94. For a subgroup J of M, if a position g is J-symmetric,
then g must commute with each operation m in J. Recall:
The fundamental principle we use in finding whether g commutes with m
can be found by examining the cycles of m. Suppose m permutes a
cycle (c1,c2,...,c[k-1],ck), so that
c2=m(c1), c3=m(c2), ..., ck=m(c[k-1]), and c1=m(ck).
For g to commute with m, we have
g(c2)=m(g(c1)), g(c3)=m(g(c2)), ..., g(ck)=m(g(c[k-1])),
and g(c1)=m(g(ck)).
So (g(c1),g(c2),...,g(ck)) is also a cycle of m. Thus g must map each
k-cycle of m to another k-cycle of m, and in the same order.
The orientation question was a lot more difficult, so we ran through a
bunch of little results. The following is a cleaned-up sample of the
sort of arguments, as I remember them. In it FRD is an unoriented
corner cubie/cubicle and FRD.D is its down-facing color-tab/facicle.
================================================================
Lemma 1: Suppose X and Y are corners, and m is in C, m(X)=Y.
Suppose g(X)=X and g(Y)=Y, and g commutes with m,
Then g applies the same twist to corners X and Y.
Proof: Let TX,TY be the clockwise 120-degree rotation of corners
cubies X and Y, respectively. Then m(TX(.))=TY(m(.)), as
can be seen by the fact that we could apply a twist to X in
place (TX) before moving it to Y with m, or we can perform
the same twist on Y (TY) after moving it. So if
g(X)=TX^k(X), then
g(Y)=g(m(X))=m(g(X))=m(TX^k(X))=TY^k(m(X))=TY^k(Y).
performing the same twist on Y as on X, QED.
Lemma 2: If g is E-symmetric, then each corner cubie remains in
its home cubicle (not considering orientation).
Proof: Supposing otherwise, take a moved cubie (without loss of
generality) to be FRD, and suppose (w.l.o.g.) it moves to
one of locations FDL, FLT, or BTL.
Case 1. If g(FRD)=FDL, consider operation m to be the
120-degree rotation about FRD.
m(FRD)=FRD, m(FDL)=FTR. So
g(FRD)=g(m(FRD))=m(g(FRD))=m(FDL)=FTR, contradicting
g(FRD)=FDL.
Case 2. If g(FRD)=FLT, then take m as in case 1; m(FLT)=BRT,
so g(FRD)=g(m(FRD))=m(g(FRD))=m(FLT)=BRT,
contradicting g(FRD)=FDL.
Case 3. If g(FRD)=BTL, then g(FRD.F) is BTL.B, BTL.T, or BTL.L.
Case 3a. If g(FRD.F)=BTL.B, then g(FRD.R)=BTL.T, by clockwise
adjacency. But m(FRD.F)=FRD.R and m(BTL.B)=BTL.L,
and g(FRD.R)=g(m(FRD.F))=m(g(FRD.F))=m(BTL.B)=BTL.L
contradicts G(FRD.F)=BTL.B.
Cases 3b and 3c work the same way.
The contradictions establish that FRD does not move, QED.
Lemma 3: If g is E-symmetric, then the twists of the four corner
cubies FRD, FLT, BLD, and BRT agree with each other, and and the other
four also agree with each other.
Proof: For any two of the four corners (e.g. FRD, FLT), there is a
120-degree rotation in E taking one to the other (e.g. the rotation
about FTR). Lemma 1 applies immediately to show the twists agree,
QED.
Lemma 4. If g is E-symmetric, then the corner cubies are all
solved, or are rotated alternately in opposite directions.
Proof: From Lemma 2, all the cubies are in their home cubicles. If
one of the sets from Lemma 3 is twisted, their total twist is the
twist of a single cubie (since there are four of them) and so must
be counteracted by having the other set twisted in the opposite
direction, which is alternate corners twisted oppositely; otherwise
all corner are solved, QED.
Lemma 5. Let T1 refer to the group that fixes the FRD-BTL axis.
Then any T1-symmetric position g must keep the FRD and
BTL cubies in their solved position, and rotated by the
same amount.
Proof: Let m be the 120-degree rotation about FRD, which is in T1.
Since FRD and BTL are the only 1-orbits of m, they are kept
in place or swapped. From the proof of Lemma 2 (which uses
the same m) they cannot be swapped. Otherwise, the two
cubies are kept in place, and 180 degree rotation about the
FL-BR axis, also in T1 fulfills the requirements of Lemma 1
to show they will both be rotated the same amount, QED.
================================================================
That's about all I feel like remembering and formalizing right now.
As you can see, it's long, mechanical, and boring. That's why we
never got around to writing it all down.
Early last year I wrote a computer program to find *all* the symmetry
groups of *all* the positions. The first part did the corners and
edges separately, counting the number of positions for each symmetry
group and permutation parity. For each of the 8! or 12! permutations,
I checked to see if the permutation commuted with some nontrivial
operation of M; if not, I just counted the appropriate number of
I-symmetric positions. Otherwise I applied orientations and counted
up the symmetry groups of each possible orientation. (It could
probably have been made to go faster, by cutting off partial
permutation or orientation generation as soon as all the non-trivial
operations were ruled out.)
In the above counts, I also kept track each time of whether the
permutation was even or odd. Then after I had the count of even and
odd permutations for corners and edges in each symmetry group, I had a
program that intersected the symmetry groups, and for each pair of
subgroups J,K, and each parity P, I added
Corners[J,P] * Edges[K,P] to Whole[J intersect K, P],
with some fancy footwork so I only needed to deal with conjugacy
classes for J and K. Then for each K, the number of whole K-symmetric
positions was Whole[K,Even]+Whole[K,Odd].
The program finished about the time I realized the application of the
Polya-Burnside theorem. Then for most of the year, I put off writing
it all up. I have Jerry to thank for reminding me to get with it, and
for useful comments and discussions on the early drafts.
Dan
---
Article 15096 of rec.arts.sf.fandom:
From: hoey@aic.nrl.navy.mil (Dan Hoey)
Newsgroups: rec.arts.sf.fandom
Subject: Re: 1995 DISCLAVE
Date: 23 Jun 1995 16:54:58 GMT
Organization: Navy Center for Artificial Intelligence
In-reply-to: drgafia@aol.com's message of 21 Jun 1995 18:42:34 -0400
drgafia@aol.com (Dr Gafia) writes:
> First, I suggest that the people probably DID understand the B&D overtones
> to what they were doing. Even so, I agree with Joseph.
If you feel compelled to suggest that, maybe you should have READ what
I WROTE with my HANDS. This is the way it looked before you addled
the formatting:
> ... I didn't try to stop it--mainly
> because I don't think the people who would really mind it recognize
> the B&D overtones--but I was not comfortable with the situation....
I'm sure the leatherly couple knew _exactly_ what their costumes
meant. On the other hand, I rather doubt the Promise-Keepers would
pick up on it quite that fast. Or were you thinking of some other
"people who would really mind it."
As for what am278@FreeNet.Carleton.CA (Joseph W. Casey) wrote, here it
is, again without the gafiod's creative word processing.
: I guess that fandom really is getting older. When I was younger one of the
: main chalenges at a convention was freaking the mundanes. You got extra
: points if you could freak fen. Of course anything you did had to be legal.
: But other than that pretty much anything went. Now, I haven't had time to
: indulge in that kind of horse play in several years, I've been too busy
: working the ocnvenions,and calming the hotel staff down....
And I'll say this about that: If what you've been doing is "calming
the hotel staff down", I envy you your job. What I've been doing is
going around in the year before the con, listening to hotel after
hotel say "Oh, you're those pervy science fiction people that all the
other hotel guests complained about last year. We don't want that
kind of convention." That makes a fan really old, really fast.
If we freak enough mundane hotel guests, we're not going to have any
hotel staff to calm down any more.
Dan Hoey Hoey@AIC.NRL.Navy.Mil
Chair, Disclave '95
---
Newsgroups: rec.puzzles
From: hoey@aic.nrl.navy.mil (Dan Hoey)
Date: 1995/06/26
Subject: Re: A cute counting problem
[ Please excuse the previous, slightly mistaken version of this
message. ]
Kanad Chakraborty wrote:
>If there are b boxes, b >= 3, arranged in a circle and we place m
>marbles, m < b, in the boxes in any arbitrary manner, prove that
>there will exist a box without any marbles that is flanked by boxes
>which together contain at most three marbles.
Barry Wolk gives a hint and David Karr gives a solution; here's
a different approach.
If there are no marbles, the solution is immediate. Otherwise, group
the circle into alternating sequences of empty boxes and a like number
of sequences of occupied boxes--there must be at least one of each
kind, since 0 < m < b. Now whenever there are two adjacent occupied
boxes, remove the less populous box and its marbles; remove either box
in case of a tie. This removes at least as many marbles as boxes, so
m < b is preserved; it also doesn't decrease the number of marbles in
the empty boxes' neighbors, so it doesn't add any new solutions.
Eventually the occupied sequences will be reduced to singletons. So
there are exactly as many occupied boxes as there are sequences of
occupied boxes, which are as many as the sequences of empty boxes,
which are no more than e, the number of empty boxes. Thus e >= b/2.
Count up all the empty boxes' neighbors' marbles. This counts the
contents of each occupied box twice, since it is the neighbor of two
empties, so we get 2m. Since 2m < 2b <= 4e, there are fewer than four
times as many marbles in empty boxes' neighbors as there are empty
boxes. Therefore one of the empties must have neighbors with fewer
than four marbles between them.
OMAR has surely noticed this argument becomes pathological in the case
that there is exactly one empty box. Of course, the difficulty can be
resolved in a number of ways, perhaps most easily by noting that in
this case each occupied box contains a single marble.
ObPuzzle 1: So what was Barry's solution, with the lemma of four
boxes containing at least three marbles?
ObPuzzle 2: Any more neat essentially different solutions?
ObPuzzle 3: If there are b boxes containing fewer than kb marbles
between them, show an upper bound for the minimum number of marbles in
the neighbors of a box containing fewer than k marbles. Or should we
be bounding the marbles in that box together with its neighbors?
Dan
Hoey@AIC.NRL.Navy.Mil
---
Article 15195 of rec.arts.sf.fandom:
From: hoey@aic.nrl.navy.mil (Dan Hoey)
Newsgroups: rec.arts.sf.fandom
Subject: Re: 1995 DISCLAVE
Date: 26 Jun 1995 16:44:35 GMT
Organization: Navy Center for Artificial Intelligence
In-reply-to: drgafia@aol.com's message of 25 Jun 1995 10:31:09 -0400
drgafia@aol.com (Dr Gafia) coughs up:
A noisome dog's breakfast of nearly unreadable and occasionally
abusive prose.
I won't attempt to quote it--he'll just reformat it into something
even more bizarre, uncomprehended, and incomprehensible--but I should
correct a few of the misconceptions he promulgated in his message:
-> The Promise-Keepers are a right-wing fundamentalist Christian group
who were sharing the hotel with Disclave. My point, in case anyone
other than the Gafioid misunderstood it, was:
_If_ the Promise-Keepers knew the dog collar and leash were
intended to indicate a sado-masochistic relationship,
_then_ they would have objected to such themes being
flaunted in public in their midst,
but I _don't_ think think the Promise-Keepers noticed the symbolism,
so I _don't_ think they minded,
so I _don't_ think they will complain to the hotel,
in which case, _I_ don't mind.
Now, Rich will possibly notice that that's roughly what he suggested
in his response to me. If so, he's finally understood it.
-> The part of my post I said "he should have read" was quoted in the
message he read, and even quoted in the message he posted, so his
claim he saw only the response to my post is a transparent excuse
for not reading what's in front of his face.
-> In my correction, I did not in any case issue a "more complete"
quotation (as he claims twice, once in quotes, as if I'd made such
a claim, which I didn't), I merely restored the formatting of the
material he quoted, removing the spurious line breaks and glyphs he
inserted when quoting. Really, I can't tell whether he's trying to
be the next e e cummings or if he's bucking for the crudzine Hogu.
Dan Hoey Hoey@AIC.NRL.Navy.Mil
Chair, Disclave '95
---
Newsgroups: rec.puzzles
From: hoey@aic.nrl.navy.mil (Dan Hoey)
Date: 1995/07/05
Subject: Re: Rubik's cube size of data file
When I wrote:
> >1. Working base 18 instead of base 32 gets you just under 4.17 bits
> > per position....
ue...@freenet.Victoria.BC.CA (Tim Browne) asks:
> Nani? There's 26 cubes! How can you only work in base 18?
I imagine the problem is to create a table showing the optimal
solution method for each position. The obvious way is to store, for
each position, the move that takes it closer to home. That would
explain why the original writer expects to need 5 bits, assuming he
counts quarter-turns and half-turns as a single move.
You don't need to store the locations of the cubies or stickers--those
are encoded to form the _index_ into the table.
I continued:
> >The actual number of positions is 43,252,003,274,489,856,000 ....
> >Now, if we manage to store only the 901,083,404,981,813,616
> >essentially different positions*....
> >[* The number of essentially different positions, up to the symmetries
> > of the cube, is not that widely known--I calculated it last year.
> > I don't know of a computationally feasible way to index into a table
> > of positions reduced by symmetries. ]
> "Urm" indeed. It appears that you also need a new abacus. The
> 43,... etc. figure *is* the number of possible positions accounting
> for symmetry. To find the number of "positions" assuming rotating
> the cube to any side in any of the cardinal directions, merely
> multiply this figure by 24. It beats me where you get this "divide
> by 48" figure from.
I'm sorry you didn't understand my remark, but before you question my
arithmetic you should perhaps try to get some understanding of what
is being calculated.
Consider the cube positions that have X's on all six sides. There are
seventeen of them. One is the Pons Asinorum, in which each edge is
swapped with its diametric opposite. In eight of them, each edge is
involved in a 3-cycle around a long diagonal axis. And in eight more,
each edge is involved in a 6-cycle in a zigzag around a long diagonal
axis.
But all you need to know to solve these is one of each of the three
kinds. If you want to solve one of the 3-cycle X positions and you
know how to solve another such, you can move the cube in space until
the one you need to solve is the one you know how to solve (up to
a uniform recoloring of the cube).
Similarly, all twelve of the positions one quarter-turn from SOLVED
can be solved using a robot that only knows how to turn the F face a
quarter-turn clockwise, provided that the robot has the ability to
move the cube in space (so that the desired face is foremost) and to
reflect the cube in a mirror (in case the desired turn is
anticlockwise). After doing so, the robot may turn the F face
clockwise and finally move (or reflect) the cube back to its original
position. So all the positions one quarter-turn from SOLVED are
essentially the same, up to conjugation by the symmetries of the cube.
My calculations showing that the number of essentially different cube
positions are in
http://www.math.rwth-aachen.de:8000/~mschoene/Cube-Lovers/
Dan_Hoey__The_real_size_of_cube_space.html
or in the cube-lovers archives
ftp://ftp.ai.mit.edu/pub/cube-lovers/cube-mail-13.gz
Though you may need to read more of the archives to understand the
nomenclature, and perhaps learn some group theory.
If you want to join the cube-lovers mailing list, you may send email
to Alan Bawden at cube-lovers-requ...@ai.mit.edu; be careful not to
bother the list itself with such administrivia.
>... So you might be able to make a table of all the positions for
>under a billion dollars. Then again, why would you want to? I've
>heard of some really strange files, but this is ridiculous!...
Well, such a file would give you an optimal solution method for any
position. Some of us think that would be a good thing. Maybe not a
gigabuck's worth, but maybe we can get the cost down to something
reasonable.
Dan Hoey
Hoey@AIC.NRL.Navy.Mil
---
Newsgroups: rec.arts.sf.written, rec.arts.sf.tv.babylon5
From: hoey@aic.nrl.navy.mil (Dan Hoey)
Date: 1995/07/05
Subject: Re: ATTN JMS:Harlan Ellison o
I will give Brian Siano the benefit of the doubt, and suppose that he
really didn't understand what I was talking about. And I will try
once more to explain the main point.
Part of the fault is certainly mine: when I said
> : * Ellison courted the adulation of fans by saying he had turned in
> : the stories to his editor, and he hadn't.
I meant to say "to his publisher". But that's not the main point.
si...@cceb.med.upenn.edu (Brian Siano) writes:
> I think that Ellison's decision to threaten legal action was a
> wrong, and as far as I know, I've never said anything to the contrary.
> But your insistence that this is some kind of "defining
> moment" for Ellison is wrong, for the simple fact that _none_ of his
> critics here has ever made any reference to the campaign of abuse
> heaped upon him by Charles Platt and Gary Groth....
If Siano counts me as a critic, then he is ignoring the words he
quoted from my article, in which I spoke of Groth's "campaign of
continual criticism of Ellison." I used the term "criticism" where
Siano uses "abuse", because I do not agree that the campaign was
abusive. As an example of the distinction, consider Groth's report of
Ellison's claim that Roddenberry would have gladly engaged in public
bestiality. I would say that Ellison's statement is _abuse_ and
Groth's report of it is _criticism_. But that's not the main point.
No matter _what_ Groth has written about Ellison, I fail to see why we
should not treat Ellison's attempt to suppress the publication of a
book as "a defining moment" (which were not my words, for all that
Siano writes them in quotes). The moment is an example of a case in
which Ellison's commitment to free speech is in conflict with his
commitment to his ego, and Ellison defines himself by protecting one
at the expense of the other.
For all Siano's claims of all the critics ignoring or denying the
"campaign of abuse", I haven't seen anyone ignore or deny it. No
one is ignoring the fact that Groth pushed Ellison's buttons. But
censorship is censorship, and it doesn't stop being censorship when
you do it to someone who says bad things about you. And when Cusick
tries to say it's not censorship, I have to wonder what censorship is
like on whatever planet he comes from. "The freedom of the press
shall not be abridged--unless you make me very, very angry."
Now, when I discussed Cusick's piece, saying
> : ... It's an incredibly long article, partly because of
> : having verbose, biased commentary interspersed with the apparently
> : factual reporting.
Siano replied
> It's a thorough article, admittedly very long for such a
> relatively small matter, but the article is critical of Ellison on
> many points. It's hardly what I'd call "biased." It's probably the
> fairest account of the whole mess.
I said the _commentary_ was biased, and I can't see how anyone could
read the piece and deny it. The commentary repeatedly decries Groth's
base motives and Platt's sordid reflexes. Siano quotes Groth's desire
for "a visceral reaction from Ellison in the person of his attorney."
But the article never demonstrates that those are their motives, and
of course it _can't_. It is certainly plausible that they honestly
believe that Ellison deserves to be criticized for what he has done.
If the article had suggested _possible_ motives, it might manage to
remain unbiased. But when it repeatedly, unsupportably, and
unconditionally describes the critics as "vicious" and "churlish", its
bias is inescapable. But I mentioned the bias only in passing, as it
makes it less convenient to read for the apparently factual reporting.
It's still not the main point.
Siano quotes a lot of Cusick's article, finally
> "Harlan Ellison was wrong to attempt to control the
> publication of _The Book on the Edge of Forever_. He was not wrong
> because [he (omitted by Siano)] is a hypocrite who gives lip service
> to free expression only to muzzle it at the first signs of
> convenience [sic in _The Gauntlet_, though I think he means
> "inconvenience"].... Let's say it again. Harlan Ellison was wrong
> to have his lawyer send that letter. No doubt he reacted viscerally
> to a situation few people were aware of. Groth had been using every
> advantage at his disposal... to annoy, cajole, incite, and otherwise
> inflame Harlan Ellison. Gary Groth went gunning for Ellison and when
> Ellison sent that lawyer's letter he may as well have said, "Shoot
> me now! Shoot me now!" And Gary Groth, sort of a vicious Elmer Fudd,
> took aim and fired."
and Siano concludes:
> Seems pretty clear to me: the article condemns Ellison for
> having sent the letter, but fairly and accurately tells the _whole_
> story. Unlike his critics.
It seems pretty clear to me that Siano has fairly and accurately
omitted my conclusions about the article, which explain just what is
wrong with the "_whole_ story" quoted above.
1. Gary Groth _does_ have a right to criticize and report on Ellison's
public behavior in the _Comics Journal_, even if he does so "to
settle old scores and private matters", even if it annoys and
inflames Ellison, and Cusick is wrong to deny that right.
2. An attempt to suppress a publication by legal threats _is_
attempted censorship, even in the face of annoyance, cajoling,
incitement, inflammation, or any other provocation, and Cusick
is wrong to deny that it is attempted censorship.
And _that_ is the main point of what is wrong with Cusick's article.
Not that it is biased (though it is, and though careless readers seem
to swallow the bias without noticing it), but that its conclusions
are nonsense.
Dan Hoey
Hoey@AIC.NRL.Navy.Mil
---
Newsgroups: rec.arts.sf.written, rec.arts.sf.tv.babylon5
Followup-To: rec.arts.sf.written, rec.arts.sf.tv.babylon5
From: hoey@aic.nrl.navy.mil (Dan Hoey)
Date: 1995/07/06
Subject: Re: ATTN JMS:Harlan Ellison o
[ My apologies to anyone who got multiple copies of the previous
message with typographical errors. ]
Dan Hoey
Hoey@AIC.NRL.Navy.Mil
---
Newsgroups: rec.arts.sf.written, rec.arts.sf.tv.babylon5
Followup-To: rec.arts.sf.written, rec.arts.sf.tv.babylon5
From: hoey@aic.nrl.navy.mil (Dan Hoey)
Date: 1995/07/06
Subject: Re: ATTN JMS:Harlan Ellison o
si...@cceb.med.upenn.edu (Brian Siano) writes:
> I once did a couple of columns about the Holocaust revisionists....
The idea of you "doing" any kind of journalism fills me with horror,
for the reasons I present below.
> Mark Twain was know throughout his career as Mark Twain;
> anyone wanting to track down Mark Twain would have had no trouble.
> _Gauntlet reported that it took them a fair amount of research to
> learn and confirm that "Gabby Snitch" was Charles Platt.
The _Gauntlet_ article reported nothing of the sort. You were fooled
by your careless reading and Cusick's misleading writing. On page
119, Cusick quotes Charles Platt:
"I've always written under my own name, or pseudonyms that are an
open secret (e.g. Gabby Snitch). I'm not modest enough to use a
pseudonym (unless a publisher insists on it and pays for it)...."
In the next paragraph, Cusick writes, "Far from an open secret,
_Gauntlet_ had a great deal of trouble confirming Platt's current
professional psuedonym [sic]...."
Of course, the difficulty in the second statement does not contradict
Platt's statement in the first (presuming, as even Cusick does, that
the publisher is paying for the use of the professional pseudonym).
The words "Far from an open secret" are of course highly misleading
here; they imply a contradiction that does not exist. I can only hope
that Cusick is being careless rather than intentionally deceptive
here. But a careful reader wouldn't have been fooled.
> (Larry Shaw's wife called Ellison in tears over)
> : >the published article.
> : Are you sure?
> Yep: confirmed by Ellison at his talk, and in the _Gauntlet_ article.
Are you "sure" Ellison isn't exaggerating, misremembering, or simply
lying? After all, he is the one who was trying to justify an act of
assault. Are you "sure" Cusick didn't just take Ellison's word for
it? What sources did Cusick quote that make you so "sure"? If you
don't know the answer, you were reporting something you have no
knowledge of, again.
> : And if some words by Harlan Ellison
> : about Poul Anderson made Karen Anderson retreat in tears,
> : should people who admire Poul Anderson punch Ellison out?
> Your analogy is faulty here: people who admire Ellison didn't
> punch Platt out.
No, a person who admired Larry Shaw punched Platt after Platt's widow
reportedly wept. What's the fault in the analogy? Or is this just
a third case of your report-without-thought technique?
> : Platt was pretty clearly ridiculing Ellison, not Shaw. I
> : certainly can understand how Shaw's wife and friends might not
> : see it that way.
> Have you read Platt's account? It was genuinely ugly, and it
> doesn't take a geniius to read it and understand Shaw's wife's reaction.
If you dare ask if we have read Platt's account, perhaps you can
answer whether _you_ have read Platt's account. Well, since you know
"it was genuinely ugly", you presumably know more about the account
than was published in _The Gauntlet_, which was a brief excerpt
without any context. And which failed to vilify Shaw in any way,
unless saying that a dying man's voice is a "croak" insults his
mellifluity. Maybe you can enlighten us with a dozen sentences
of "Platt's account", including the context not reported in the
_Gauntlet_. Or maybe you were just claiming knowledge you don't
have, for a fourth time.
Hello? I noticed the door flapping in the wind. Is anyone home?
Dan Hoey
Hoey@AIC.NRL.Navy.Mil
---
Newsgroups: rec.puzzles
From: hoey@aic.nrl.navy.mil (Dan Hoey)
Date: 1995/07/07
Subject: Re: NEW SORT METHOD!! FAST!!!!!! NEW??
It's worth mentioning that the information-theoretic lower bound is
only _linear_ in the usual metric--the size of the input. For that
Omega(N log N) is actually the time to sort N items of size log N.
Of course, ordinary radix sort on fixed-length records is also linear
in the size of the input.
A few years back, Dan Bernstein was pushing a form of dynamic radix
sort that (as I recall) is linear in the size of the problem for
variable length records. He also challenged the theorists to come up
with a sorting problem that could not be recast into a radix sort on
fixed-length records with only linear time costs. I didn't follow all
the resulting brouhaha, but it at least seems plausible to me.
Dan Hoey
Hoey@AIC.NRL.Navy.Mil
---
Newsgroups: rec.puzzles
From: hoey@aic.nrl.navy.mil (Dan Hoey)
Date: 1995/07/09
Subject: Re: Marlow's Units, Unit One - How? [SPOILER]
russo...@wanda.pond.com writes:
> Kilogram is mass, not weight. Pound, on the other hand, is weight.
> Convert it to the rather strange unit slug-meter/second^2, and all
> cancels but the slug.
Close. A pound is actually a slug-foot/second^2. Well, you _could_
convert it, but then you'd have to convert the miles, too.
Dan
---
Date: Sun, 09 Jul 95 19:53:10 -0400 (EDT)
From: Dan Hoey
To: Cube Lovers
Subject: Re: 3x3x3 Cubes for Sale
"Jerry Bryan" writes:
> ... I couldn't see inside the box to verify this, the Face centers
> seemed to be marked in such a way as to support the Supergroup.
Just as well, you'd have been disappointed. As I wrote on 8 Jan 92,
: While most people are content to make each face a solid color, some
: cubes have markings that display whether the face centers are twisted
: with respect to the rest of the cube.
: [This has recently been done commercially in an spectacularly
: braindamaged way, in a product known as ``Rubik's cube--the
: fourth dimension'' or some such nonsense. The mfrs have marked
: only four face centers, breaking symmetry while they fail to show
: the surprising invariant of the Supergroup. What bagbiters!]
Rubik's note about the size of the problem says it is 4^4 times
bigger than the regular problem.
And it could have been 4^(11/2).
Dan
Hoey@AIC.NRL.Navy.Mil
---
Newsgroups: sci.math
From: hoey@aic.nrl.navy.mil (Dan Hoey)
Date: 1995/07/10
Subject: Re: Math involved with Rubik's Cube
dmor...@undergrad.math.uwaterloo.ca (David Morton) writes:
> ... does anybody have information on mathematical analysis of the
> Rubik's cube? I heard that it was proven that the best solution for
> a given cube would be less then ~50 twists (a twist being 90 degree
> turn of a side)....
I think the best upper bound now known is michael reid's. In January
1995, he showed that 42 moves suffice (or 29 moves if you also allow
180-degree turns). You can see his report of it on
http://www.math.rwth-aachen.de:8000/~mschoene/Cube-Lovers/michael_reid__new_upper_bounds.html
also available in
ftp://ftp.ai.mit.edu/pub/cube-lovers/cube-mail-14.gz
If you want to join the mailing list where we discuss this and other
aspects of cube analysis, send email to Alan Bawden at
Cube-Lovers-Requ...@AI.MIT.Edu
and he'll put you on the list.
Dan Hoey
Hoey@AIC.NRL.Navy.Mil
---
Newsgroups: sci.math
From: hoey@aic.nrl.navy.mil (Dan Hoey)
Date: 1995/07/10
Subject: Re: What is 0 to the power 0???
t...@cco.caltech.edu (Toby Bartels) writes:
> The natural number 0 is the empty set {}.
> The integer 0 is the diagonal set {(0, 0), (1, 1), ...} of the
> natural numbers. ...
No, I'm sorry, but this just won't do. We definitely want the natural
numbers to be a subset of the integers, and so this sort of naive
construction is just not good enough.
The usual technique is after you form this set of proto-integers Z*, a
partition of NxN, you have to show that there is a subset Z*[N] that
acts just like the integers. Then define Z = ( Z* \ Z*[N] ) U N, with
the natural isomorphism to Z*. This is called "embedding N in Z* to
form Z". Similarly, you have to embed Z into Q* to form Q, and Q into
R* to form R, and R into C* to form C.
Of course, this stupid, wasteful exercise is only given to quibble
artists who try to assert some stupid, wasteful distinction between
e.g. the natural number 0 and the real number 0. Those of us who knew
they were the same all along don't need that sort of noise.
Dan Hoey ZERO is REAL unless declared INTEGER.
Hoey@AIC.NRL.Navy.Mil NOUGHT is INTEGER unless declared REAL.
---
Newsgroups: sci.math
From: hoey@aic.nrl.navy.mil (Dan Hoey)
Date: 1995/07/10
Subject: Re: Cubic equations with real roots
rbury@delphi.com writes:
> The standard solution for cubic equations involves the cube root of
> imaginary numbers when there are three distinct real roots....
> Does anyone know of a formula for the
> solution of a cubic equation with real coefficients that works when
> there are three real roots and involving only the basic arithmetic
> operations and the extraction of roots of real numbers?
No, no one does, because there is no such formula. In particular, if
a cubic equation with rational coefficients has three real irrational
roots, then the roots are not expressible in real radicals.
I unfortunately don't know the proof of this, nor can I give you an
exact reference. But the topic is called "equation theory", and there
were a lot of books written about it about 70-100 years ago. I've seen
this stated, with a proof that I didn't understand, in such a book.
Dan Hoey
Hoey@AIC.NRL.Navy.Mil
---
Newsgroups: rec.puzzles
From: hoey@aic.nrl.navy.mil (Dan Hoey)
Date: 1995/07/12
Subject: Re: Rubic's 2x2x2 3x3x3 4x4x4 ... nxnxn virtual cubes
Somehow, I suspect that yet another person will chime in with the
Frequently Asserted Quibble that 7x7x7 cubes are impossible to build
physically (and anyway, they aren't, see the archive).
You wrote:
> For people who are interested in solving nxnxn rubic's cube, I
> developed a small program that, using operators, can turn on a nxnxn
> cube. The nice thing is that operators can be combined and inverted,
> leading to combined oprators for example of the form P Q P-1Q-1
> which leave the whole cube in tact but just shuffles three faces
> or corners, or whatever.
You might want to put it on the Cube-Lovers archive server, in
ftp://ftp.ai.mit.edu/pub/cube-lovers/contrib. Send email to Alan
Bawden (Cube-Lovers-Requ...@AI.MIT.Edu) to see how to do so. He
can also add you to the Cube-Lovers mailing list, if you like.
Cube-Lovers has a lot of discussion relative to Rubik's cube and
variants. Its has extensive archives of the discussion, which has
been going on for fifteen years today.
> Using this program I was able to solve the 5x5x5 cube. By hand this
> would be imposible because you can't distiguish the faces around the
> middle points.
Well, if they matter, you can distinguish them. But even better, you
can mark up the cube. For instance, if you cut the corners of sixteen
colortabs on each face, like this
+----+----+----+----+----+
| | | | | |
| | | | | |
+----+----+----+----+----+
| | | | | |
| | / \ | / \ |
+----+--+ +--+--+ +--+
| | \ / | \ / |
| | | | | |
+----+----+----+----+----+
| | | | | |
| | / \ | | |
+----+--+ +--+----+----+
| | \ / | | |
| | | | | |
+----+----+----+----+----+
then there's only one way to solve the cube so the cuts all match up.
> Anyone who's interested can send a mail to:
> s.s.op.de.b...@phys.tue.nl
> and will get the program in turbo pascal.
I'm sending this to the address you posted from; please let me know
you received it, or I'll try the other address.
At any rate, please DON'T email me your program. I don't use this
address for moving programs around, only for discussion.
Dan Hoey
Hoey@AIC.NRL.Navy.Mil
---
Newsgroups: rec.arts.sf.fandom
From: hoey@pooh.tec.army.mil (Dan Hoey)
Date: 1995/07/12
Subject: Re: What LACon &c. (long reply)
Mr John Bray (ucfa...@ucl.ac.uk) wrote:
: I do not feel that fanzines are part of my fannish involvement, and feel
: no desire to subsidise the travel costs of people I've never heard of....
I am shocked--shocked!--to hear that Mr John Bray is having his
admission monies hijacked to support an activity in which he is not
personally involved. I will be right over to eject those freeloading
faneds, once I solve a slightly more pressing problem (some dealers,
it seems, have taken to supplementing their incomes by selling--you
guessed it--books! And in the Huxter Room, no less!)
Dan
Hoey@AIC.NRL.Navy.Mil
---
Date: Wed, 12 Jul 95 18:02:51 -0400 (EDT)
From: Dan Hoey
To: Cube Lovers
Subject: Happy birthday
(Sorry to have neglected the last thirteen).
\ \ \ \
/\ /\ /\ /\
/ / \ / / \ / / \ / / \
\/ /\ \/ /\ \/ /\ \/ /\
\ / / \ \ / / \ \ / / \ \ / / \
{} \/ {}/\ \/ {}/\ \/ {}/\ \/ /\
{} \ {/ / \ \ {/ / \ \ {/ / \ \ / /
{} {} {\/ {}/\{\/ {}/\{\/ {}/\ \/
{} {} {}\ {/ /{}\ {/ /{}\ {/ / \
+_------{}+_--{}--{}{}--{\/-{}{}--{\/-{}{} {\/ {}
| `-_ {} `-{} {}{}`-{}\ {}{}`-{}\ {}{}`-{}\ {}
|S `+_------{}+_--{}--{}{}--{}--{}{}--{}--{}{} {}
| | `-_ {} `-{} {}{}`-{} {}{}`-{} {}{}`-{}
| S |A `+_------{}+_--{}--{}+_--{}--{}+_--{}--{}+_
| | A|M`-_ {} `-{} {} `-{} {} `-{} {} `-_
+_ S| | M `+_------{}+_------{}+_------{}+_-------`+_
|L`-_ |A |M M|*`-_ {} `-_ {} `-_ {} `-_ `-_
| L `+_ A| M |* * `+--------`+--------`+--------`+--------`+
|L L|O`-_ |M M|* * *| | | | |
| |O O `+_ M |* *| | | | |
|L L|O O O| `-_M|* * *| Happy | Birth | day | to |
+_ L |O O O| `+_ * *| | | | |
| `-_L|O O O| Y | `-_*| | | | |
|H `+_ O O| |D `+---------+---------+---------+---------+
| H | `-_O| Y | D| | | | |
|H H| `+_ | D | | | | |
| H | |R`-_ |D | Cube | Lovers | @ | MIT |
+_ H| E |R `+_ D| | | | |
|W`-_ | |R R R|E`-_ | | | | |
|W `+_ |R R|E `+---------+---------+---------+---------+
|W W W|A`-_ |R R R| E E| | | | |
|W W W|A `+_ R|E E E| | | | |
|W W W| A A| `-_R|E E | 15 | Years | 1659 | Messages|
+_ W|A A|S `+_ E| | | | |
`-_W|A A | S | `-_E| | | | |
`+_ A|S S S| `+---------+---------+---------+---------+
`-_A| S | | | | | |
`+_ S| | | | | |
`-_ | | Many | Happy |Restores | |
`+_ | | | | |
`-_ | | | | |
`+---------+---------+---------+---------+
--Dan
---
Newsgroups: rec.arts.sf.fandom
From: hoey@aic.nrl.navy.mil (Dan Hoey)
Date: 1995/07/15
Subject: Re: What LACon &c. (long reply)
yb...@panix.com (Ben Yalow) writes:
> Pam Wells writes:
> >Have there been no women chairs of Worldcon?
> There have been a number. The most recently selected (and I don't know
> what tense to use here) will be Karen Meschke (LonestarCon 2 - 1997).
> The most recent really past one was Kathleen Meyer (Chicon V - 1991).
And for anyone who wants an unambiguous future tense, the next
possible future chairpersons-of-the-feminine-persuasion could be
Peggy Rae Pavlat (if Baltimore in 98 wins) or Jill Eastlake (co-
chair with Donald Eastlake III, if Boston in 98 wins). If Atlanta
or Niagara Falls wins you get chairmales Bill Ritch or Joe
Maraglino, respectively. One-and-a-co out of four ain't bad.
Dan
Hoey@AIC.NRL.Navy.Mil
---
Newsgroups: sci.math
From: hoey@aic.nrl.navy.mil (Dan Hoey)
Date: 1995/07/19
Subject: Re: group theory
fc3a...@rzaix02.uni-hamburg.de (Hauke Reddmann) writes:
> |> Assume that I have a matrix scheme where every element occurs
> |> in every row and column only once, say:
> |> 12345
> |> 21534
> |> 45213
> |> 34152
> |> 53421
> |> Question: Can this be always interpreted as a group table?
...
> |> WARNING: I didn't say that the row and column headings of
> |> this example are 12345! You can take them as you like to
> |> make the scheme a group.
h...@cscsun3.larc.nasa.gov (Ed Hook) replies:
> ... Do you mean that I can, in effect, arbitrarily permute the
> rows and columns in my attempt to produce a group table ? If so,
> it seems pretty clear that I can succeed -- in the nxn case, I
> will eventually arrive at something isomorphic to the additive
> group of the integers mod n.
No, you can't, and you can't do so in the particular example above.
I will show that the rows of a group table cannot be arbitrary
permutations of each other, even if the table is transformed by having
(possibly different) permutations applied to its rows and columns.
Suppose we label the the rows 1,2,3,4,5, and the columns in some
possibly different order, and refer to the element in row j, column k
as A[j,k]. If each number j in 1,2,3,4,5 refers to a group element
f(j), and this is a group table, then f(A[j,k])=f(j) f(k) for all j,k.
Then for all j,k,x
f(A[k,x]) = f(k) f(x)
= f(k) f(j)' f(j) f(x)
= (f(k) f(j)') f(A[j,x])
which is to say that the row A[k,*] is the permutation of the row
A[j,*] induced by multiplication by (f(k) f(j')). Multiplication by
a group element induces a permutation whose order is the order of the
group element, which must divide the order of the group. In the given
example, consider the second row as a permutation of the first: it
permutes the elements in disjoint cycles as (1,2)(3,5,4). So since
the inter-row permutation has order 6 the table cannot be transformed
(by row/column permutations) into a group table.
The question remains, if we require that the inter-row perrmutations
have orders dividing the side of the table, whether a row/colunn
transformation into a group table exists. If not, we might consider
the complete graph whose vertices are the rows of the table, and with
edges labelled by the order of the inter-row permutations. If that
graph is isomorphic to the graph of a group table, must there be a
transformation between them? If not, we could even require that the
permutations be labelled by the conjugacy class of the permutations
(i.e., the multiset of lengths of its disjoint cycles). In any of the
three cases, we might additionally require a similar condition on the
inter-column permutations.
For a counterexample, we might look for a square matrix of prime side
p, each of whose rows is a cyclic (i.e., order-p) permutation of each
other row, and similarly for the columns. Must we be able to permute
the rows and columns to form the group table for the group of order p?
I have my doubts, but I don't have a counterexample.
Dan Hoey
Hoey@AIC.NRL.Navy.Mil
---
Newsgroups: rec.puzzles, rec.games.abstract
Followup-To: rec.games.abstract
From: hoey@aic.nrl.navy.mil (Dan Hoey)
Date: 1995/07/19
Subject: Re: Silverman's South American Game
I've set followups to rec.games.abstract, where such games are
discussed.
> In his book _Your move_ (McGraw Hill 1971), David Silverman
> introduced a 2-person coloring game played on the map of South
> America: the two players take turns coloring (with just one color)
> the 13 countries under the restriction that each player may color
> only a country that has no common frontiers with a previously
> colored country; the last player who can color a country is the
> winner.
In the 1991 Dover edition, the game is called "Monochrome", certainly
a more descriptive name.
For people who don't have the book, or a map of South America, here's
the adjacency graph (DG and RG are Dutch Guiana and British Guiana,
which don't appear in my copy of ISO3166).
__________BR__________
/ / / / /\ \ \ \ \
/ / / / / \ \ PY\ \
/ / / / / \ \ / \\ \
GF-DG-RG-VE-CO----PE-BO----AR-UY
\ / \ \ /
EC \_CL_/
> The game can be won, of course, by the first player who should, on
> his first move, color Brazil (thereby leaving only Chile and Ecuador
> which don't have a common border).
> Besides giving this trivial strategy, Silverman asks whether there
> exist other [winning moves]. Silverman argues that there do exists
> such countries but opines that to determine all of them would
> require the aid of a computer.
> However, in my paper _The South American Game_ (Mathematics
> Magazine, Vol 50, #1, January 1977, pp. 17-21), I showed that all
> these countries can be found by using graph-theoretical concepts,
> i.e., by analysis of kernels (you _don't_ need a computer for this
> task); besides Brazil, there are indeed two other countries which
> have the required properties (my paper also showed that the misere
> form of the game has a unique winning opening move).
I was able to discover those countries by hand using the techniques I
learned from Conway's _On Numbers and Games_ and Berlekamp, Conway,
and Guy's _Winning Ways_. But I don't see that you're not going to
eventually need a computer. Even to play this game with strings
(simply- connected graphs of maximum degree 2) you will have to learn
to play Dawson's Chess, which is periodic with degree 34 even in
normal play. And the (misere) options of the above game include
*3+*2={*2+*2,*3,*2} and {*2+*2,*3,*2,*1,*0}, which would overwhelm
hand analysis if the game gets a little larger.
The only general simplifying rule I noticed (outside of the usual
Sprague-Grundy theory) is
o
|\ xx xx
o-xxxx = o-xxxx
xx xx
where the xxx is any position such to which the o's are connected
identically.
> In my paper I raised a few questions of a more theoretical nature
> concerning such games in general, but also suggested to play a
> similiar game on the map of Africa or Europe. Since I have not done
> such an analysis myself, I would like to know whether someone has
> carried out this task...
I haven't tried Africa. and I suspect Europe may currently be
undecidable (for non-technical reasons).
> PS: Just in case someone has seen my article: in Fig.1, the graph
> corresponding to the map of South America was screwed up by the
> publisher but it can be corrected quite easily.
Was this the "Chile problem" that Silverman apologized for?
Dan
---
Newsgroups: rec.puzzles
From: hoey@aic.nrl.navy.mil (Dan Hoey)
Date: 1995/07/20
Subject: Re: tough math puzzle ! ?
sch...@isi.ee.ethz.ch (Hanspeter Schmid) writes:
> Take the following equation:
> f1*f2 + f2*f3 + f3*f1 = 0 (1)
> Each of the fi (i=1..3) is of the form
> fi = ai + x*bi (i=1..3)
> Then (1) is a quadratic equation in x. Can you show that (1) always
> has real solutions if all coefficients ai and bi are >=0 ?
No, there are no solutions if all bi=0 and at least two ai>0.
Even if we require all ai,bi > 0, equation (1) may have only one
(real) solution. For instance, if f1=4+x, f2=8+2x, f3=12+3x, then the
equation is 11(4+x)^2=0, whose only zero is x=-4.
But as others have shown, if the zeroes of the fi are distinct, then
there are two distinct real zeroes of (1).
Dan Hoey
Hoey@AIC.NRL.Navy.Mil
---
Newsgroups: uk.misc, rec.puzzles, sci.physics
From: hoey@aic.nrl.navy.mil (Dan Hoey)
Date: 1995/07/20
Subject: Re: Cool: WH Smiths. Marvelous people
Charles Bryant writes:
[ and I haven't verified his attributions]
> Ian Robert Walker wrote:
> > st...@firthcom.demon.co.uk "Steve Firth" writes:
> >> Well I'm labouring under the impression that this could be
> >> achieved using the Peltier effect (as mentioned elsewhere). The
> >> hot and cold junctions need to be electrically connected, but not
> >> physically close.
> >And the warm junction would have to be outside the room, this is
> >now the same as mounting the warm heat exchanger outside the room,
> >ie air conditioning unit. But now the room is the refrigerator, it
> >does not contain a refrigerator and therefore the original problem
> >can not be done.
You can certainly insulate one part of the room from another, and call
the partition you cool the "refrigerator". Well, to be linguistically
exact, you would have to cool the partition using a working fluid
which you repeatedly (re-) cool (-frigerate) using a third partition
cooled by the Peltier effect.
> The Peltier effect was what I had in mind. I would not consider the
> warm junction to be part of the fridge, since the wires don't carry
> anything except electric current.
I was under the impression that the amount of current you needed to
run a Peltier junction was such that you could achieve the same effect
by *heat* conduction through the wires.
> To make it even more interesting, replace the two wires with only one.
> The other is chopped short (inside the room) and sharpened to a point.
> The wire which enters the room is charged to a high voltage, causing
> a current to flow due to the charge leaking from the sharp point. the
> net effect is that the junction still cools, while the room acquires
> a net charge (or maybe the electrons pass through the wall and fly
> off into space.
> Does this work? (I don't see why not) and where does the heat go?
If the electrons "pass through the wall" then the wall is the other
wire. If not, then I imagine the heat comes out the engine that
charges the room to its unbelievably high unimaginably rapidly
increasing potential. That's got to take a _lot_ of work.
Dan Hoey
Hoey@AIC.NRL.Navy.Mil
---
Newsgroups: rec.games.abstract
Followup-To: rec.games.abstract
From: hoey@aic.nrl.navy.mil (Dan Hoey)
Date: 1995/07/20
Subject: Re: Silverman's South American Game
hoey@aic.nrl.navy.mil (Dan Hoey) writes:
> For people who don't have the book, or a map of South America, here's
> the adjacency graph (DG and RG are Dutch Guiana and British Guiana,
> which don't appear in my copy of ISO3166).
Sorry, I should have checked a dictionary. British Guiana is now
called Guyana (GY), and Dutch Guiana is Suriname (SR). So the
adjacency graph of South America is
____________BR__________________
/ / / / / \ \ \ \ \
/ / / / / \ \ PY \ \
/ / / / / \ \ __/ \__\ \
GF-SR-GY-VE-CO--------PE--BO--------AR--UY
\ / \ \ /
\_EC_/ \___CL___/
By the way, Oskar Itzinger's address "os...@opec.org" bounces mail.
for the unusual reason that "oskar, origin NGM, event# 319, subevent#
0, explanation Address doesn't refer to a known recipient."
Dan Hoey
Hoey@AIC.NRL.Navy.Mil
---
Newsgroups: rec.games.abstract
From: hoey@aic.nrl.navy.mil (Dan Hoey)
Date: 1995/07/20
Subject: Re: Silverman's South American Game
Last night, I wrote about the "Monochrome" game in which players take
turns coloring vertices of the graph:
_______________BR_________________
/ / / / /\ \ \__ \ \
/ / / / / \ \ __PY__\ \
/ / / / / \ \ / \\ \
GF--SR--GY--VE--CO------PE--BO--------AR--UY
\_ _/ \ \__ __/
EC \_____CL
without coloring two adjacent vertices, until no further moves are
possible.
I mentioned:
> And the (misere) options of the above game include
> *3+*2={*2+*2,*3,*2} and {*2+*2,*3,*2,*1,*0}, which would overwhelm
> hand analysis if the game gets a little larger.
But the latter, I'm afraid, is due to a clerical error. The only
misere options are *0, *1, *2, *3, *5, and *3+*2 (modulo undiscovered
errors).
You may enjoy finding the three normal-play wins and the unique
misere-play win in the above graph. But perhaps we should add an
isolated UK to the above graph (for the Falklands), giving us two
normal-play wins and four misere wins.
Does anyone have a generally-accepted adjacency graph for Africa?
Dan
Hoey@AIC.NRL.Navy.Mil
---
Newsgroups: rec.puzzles
From: hoey@aic.nrl.navy.mil (Dan Hoey)
Date: 1995/07/27
Subject: Re: angle trisection
k...@cs.cornell.edu (David Karr) writes:
(with respect to the constructable regular polygons being the
triangle, pentagon, 17-gon, and 65537-gon)
> I was under the impression that there are other theoretically
> constructible polygons, but memory fails me.
The 257-gon is also constructable.
I'm pretty sure the only constructable p-gons for p prime are for
Fermat primes p, of the form 2^2^n+1. The known Fermat primes have
n=0,1,2,3,4; the Fermat numbers n=5,6,...,21 are composite (and so not
constructable). While no one has a proof, there are heuristic reasons
for believing there are no other Fermat primes.
> Anyway, certainly the following angles are constructible:
> k*180/(2^m 3^n 5^p 17^q 65537^r)
> for any integers k, m, n, p, q, r.
No, the integers n, p, q, and r may not exceed 1. For instance, a
nonagon is not constructable.
> Replace the 180 by 540 (i.e., multiply by 3) and you have a rather
> large list of "trisectable" angles.
The problem with this and other posted solutions is that the given
angle is not used in the "trisection". But this need not be so. For
instance, an angle of 180/7 degrees can be trisected, even though an
angle of 60/7 degrees cannot be constructed from scratch. In fact,
any angle of 180 m/n degrees can be trisected, unless n is a multiple
of 3.
Obpuzzle 1 (easy). How?
Obpuzzle 2 (hard). Are there any other trisectable angles?
Dan
Hoey@AIC.NRL.Navy.Mil
---
From hoey@AIC.NRL.Navy.Mil Mon Jul 31 00:31:54 1995
From: hoey@AIC.NRL.Navy.Mil
Date: Mon, 31 Jul 95 00:30:50 EDT
To: risks@csl.sri.com (RISKS Forum)
Cc: Karl Reinsch , blb@panix.com, doug@ss2.digex.net,
dragon@access4.digex.net, esr@snark.thyrsys.com, hlavaty@panix.com,
nancyl@universe.digex.net, kfl@access.digex.net
Subject: Re: Woman electrocuted using hotel card-key
In RISKS DIGEST 17.20, Karl Reinsch writes:
> The Washington Post on Tuesday, 27 June 1995, tells of an
> 18-year-old Cincinnati woman who was electrocuted Friday at a New
> Carrollton hotel. Police said that she was barefoot, wet, and
> standing on wet concrete. The door was apparently charged with
> electricity from a faulty air-conditioning unit in the wall near the
> door.... ``They found a faulty air conditioner emitting some sort of
> electric charge, and the charge was transcending to the door." ....
This is the hotel that hosted the Disclave science fiction convention
from 1984 to 1991, and so this incident was much on the minds of the
Washington Science Fiction Association at its meetings last month.
The most coherent version I heard was that the faulty air conditioner
had electrified the wet concrete walkway, while the doorknob was
(unfortunately) properly grounded. I suppose it could be considered a
technological risk that the use of card-key entry systems has led to
grounded doorknobs.
Dan Hoey
Hoey@AIC.NRL.Navy.Mil
---
From hoey@AIC.NRL.Navy.Mil Mon Jul 31 00:39:04 1995
From: hoey@AIC.NRL.Navy.Mil
Date: Mon, 31 Jul 95 00:38:16 EDT
To: kfl@access.digex.net
Cc: blb@panix.com, doug@ss2.digex.net, dragon@access4.digex.net,
esr@snark.thyrsus.com, hlavaty@panix.com, nancyl@universe.digex.net
Subject: Re: Woman electrocuted using hotel card-key
Thanks, KFL, for bringing the story to our attention. But please note
Eric Raymond's correct address (esr@snark.thyrsus.com) and my more
usual one:
Dan Hoey
Hoey@AIC.NRL.Navy.Mil
From: risks@csl.sri.com (RISKS Forum)
Newsgroups: comp.risks
Subject: RISKS DIGEST 17.21
Date: 31 Jul 95 16:17:17 GMT
Date: Fri, 28 Jul 1995 18:01:44 -0600
From: William Kucharski
Subject: Re: Woman electrocuted using hotel card-key
I have to object to the inference that the woman was somehow electrocuted
because she was using a card key lock.
For those familiar with the VingCard system, there is NO WAY the woman could
have been electrocuted by the lock itself, as the card key is
(nonconductive) plastic. The woman was likely electrocuted when she grabbed
the metal doorknob.
If a faulty A/C caused the problem by causing the door to acquire a charge
(obviously a metal door), she would have been electrocuted even if the hotel
had used a conventionally keyed door lock (and would have most likely been
zapped when she inserted the key into the lock).
An additional issue is the fact that most hotels have metal door frames (to
make it more difficult for a door to be kicked in), meaning that mere contact
with the door FRAME would most likely have been fatal.
William Kucharski kucharsk@drmail.dr.att.com
[also commented further on by various others, including
Jim Garrison , and
Dan Hoey , who added (among other things),
This is the hotel that hosted the Disclave science fiction convention
from 1984 to 1991, and so this incident was much on the minds of the
Washington Science Fiction Association at its meetings last month.
... I suppose it could be considered a technological risk that the
use of card-key entry systems has led to grounded doorknobs. Dan Hoey
PGN]
---
Newsgroups: rec.puzzles, alt.radio.networks.npr
Followup-To: rec.puzzles
From: hoey@aic.nrl.navy.mil (Dan Hoey)
Date: 1995/09/11
Subject: Re: NPR puzzle for 9-10-95.
Richard Renner writes:
> The on-air puzzle consisted of reversals. Will gave Jay pairs
> of clues. The first clue is a single word. Spell that word
> backward and get a two word phrase that answers the second clue.
> For example, if Will said "Layer of the skin and TV's talking
> horse", the answer would be derm and Mr. Ed....
After the puzzle was done, Liane mentioned that she didn't expect to
live to see the reign of Anne the Fourth. I wonder whether this
question was one Will didn't have time to pose, or if Liane is sharper
than I'm giving her credit for. And I wonder how it would be posed.
Cluing the city is easy (in any number of ways) but I can't think of a
clue for the hypothetical monarch.
Dan
Hoey@AIC.NRL.Navy.Mil
---
Newsgroups: rec.puzzles
From: hoey@aic.nrl.navy.mil (Dan Hoey)
Date: 1995/09/15
Subject: Re: In the Bag! (spoiler)
spu...@pomona.edu writes:
> Consider a bag which can contain all the natural numbers...
But will only need to hold arbitrarily large finite subsets....
> Given any number in the bag, you may add its prime factors to the bag.
> Given any two (not necessarily different) numbers in the bag, you may
> concatenate those numbers and place the new number in the bag.
> The bag begins with the number 1 inside. Assume that you may use any
> number in the bag any number of times.
> Which numbers is it not possible to get into the bag? How few steps
> can you get various numbers into the bag? Try 23, it's the most
> difficult one I've had so far.
It's clear we can get any repunit (10^k-1)/9 simply by concatenating 1s.
Every prime p>5 is a factor of the repunit (10^(p-1)-1)/9, so we can
get all such primes. We can also get 3 as a factor of (10^3-1)/9.
And so we can get any number formed by concatenating ones, threes, and
primes greater than five.
Since we can't any multiples of 2 or 5 by concatenating such numbers,
we cannot get 2 or 5 as prime factors. So the concatenates of ones,
threes, and primes greater than five are all we can get.
The above does not address minimizing the steps we need. For
instance, we can form 11, 111, 3, 13, 1311, 23 in 7 steps. I don't
know if that's optimal.
Dan
Hoey@AIC.NRL.Navy.Mil
---
Newsgroups: rec.puzzles
From: hoey@aic.nrl.navy.mil (Dan Hoey)
Date: 1995/09/20
Subject: Re: cutting sticks - an algorithm?
"K.J.Saeger" writes:
(unfortunately failing to cite fa...@cs.utwente.nl (Frans F.J. Faase)
as the originator of the puzzle.)
> Problem Statement:
> You are given m sticks with integer lengths
> Sum of lengths = n(n+1)/2
> No stick is shorter than n
> Cut the sticks so as to produce sticks of length 1,2,3...n
> Let's take the sticks in non-increasing order....
> n(n+1)/2 <= L1 <= L2 ...<= Lm <= n
Of course, you mean ">=" instead of "<=".
> Define: c(i,j) = 1 if stick Li is used to produce a cut length of j
> = 0 otherwise
...
> Of all possible combinations of c(1,j) choose the set that minimizes
> the function:
> j=n
> ____
> \
> F1 = > c(1,j)*2^(-i)
> /___
> j = 1
Presumably you mean 2^-j, not 2^-i.
> Repeat for all sticks Li, remembering that the Sum on i of c(i,j) =
> 1 for each j (this means that exactly 1 stick of length 1 is
> produced).
Which is to say, we minimize Fi over all partitions of Li that do not
conflict with the already chosen partitions of L1,L2,...,L(i-1).
> Perhaps the proof can be based on a binary representation of the
> system (as suggested by function F)?
I'm sorry, but function F does not suggest "binary representation" to
me. All it means is that we maximize the minimum part of Li, breaking
ties by maximizing the next smallest part, and so on. To see that
this is so, just verify that 2^-i > 2^-(i+1) + 2^-(i+2) + ... + 2^-n,
so that no way of choosing larger parts can make up for a suboptimal
choice of the smallest part. I would say that this is one way of
interpreting Dave Ring's suggestion to break successive sticks into
the "midmost possible" parts.
This method also fails to be a closed form, because it still involves
an exponential search to minimize Fi.
It also fails to be a solution: For n=15, it fails to divide sticks
22, 18, 16, 16, 16, 16, and 16. The first two steps divide 22=12+10
and 18=11+7, which is already insoluble: The numbers 15, 14, 13, 9,
and 8 must then be distributed at most one each among the 16s, and
then the numbers 6, 5, and 4 cannot all be placed. The problem can be
solved as 22=13+9, 18=10+8, 16=15+1=14+2=12+4=11+5=7+6+3. A similar
problem occurs when the largest two sticks are 21 and 19. The midmost
solution starts by creating the same unsolvable configuration, but a
solution exists: 21=12+9, 19=11+8, 16=15+1=14+2=13+3=10+6=7+5+4.
I'm still far from convinced that this problem is solvable in general.
I have verified it up to n=24, but I don't have a lot of insight into
what can happen with large n.
Dan
Hoey@AIC.NRL.Navy.Mil
---
Newsgroups: sci.math, rec.puzzles
From: hoey@aic.nrl.navy.mil (Dan Hoey)
Date: 1995/09/21
Subject: Re: cutting sticks problem (puzzle)
fa...@cs.utwente.nl (Frans F.J. Faase) writes:
> I have made a WWW page about the problem, that contains a summary of the
> threat, with some extra information. Please have a look at:
> http://www.cs.utwente.nl/~faase/cutsticks.html
Here are some comments on that web page.
> The formal description of the problem consists of proving the
> following conjecture:
> For all natural numbers n, and any given sequence a_1, .., a_k of
> natural numbers greater or equal n of which the sum equals
> n(n+1)/2, there exists a partitioning (P_1, .., P_k) of {1, .., n}
> such that sum of the numbers in P_i equals a_i, for all 1<=i<=k.
Except the last should be coded "1<=i<=k" so that all web
readers will show it.
> The problem is special case of the knapsack problem, which is stated
> as: given a number of bags with given size, can a number of
> objects be fitted into the bags. I thought that is was shown that
> the decidability of the knapsack problem is NP-Complete. But
> although knapsack problems are generally speaking hard to solve
> the class that we propose here, seems relatively easy to do.
In the standard encoding, some knapsack problems are easy to solve.
In particular, if the total bag size n(n+1)/2 is at most polynomial in
the problem size S, then the problem is easy (PTime). This occurs
here, since S is at least the number of bags, k. A similar approach
forces me to withdraw my comment that Saeger's method requires an
exponential search.
I should notice that this problem admits a much more compact encoding,
with only the parameter "n" being specified in log(n) bits, since we
are implicitly quantifying over all the appropriate partitions of
n(n+1)/2. Of course, if the conjecture is true, there is a
constant-time recognizer. And if not, there is a O(log(n)) time
recognizer, though we may not be able to prove what it is.
h...@cix.compulink.co.uk (Hugo Van der Sanden) wrote
> 4 <= k <= n/2 + 1
> n+1 <= a_i <= 2n-2 (for i in 1 .. k)
> a_i >= n+2 (for some i)
> n >= 9
These also need to have the "<"s changed to "<"s on the web page.
Also, the first inequality can be made sharper by using the second
and third inequalities:
(n+2)/4 <= k <= (n-2)/2
This is actually a little looser for n=9,10, but computer search has
already shown n >= 26.
> POSSIBLE PROOFS
> + Proof by probablistic arguments. The number of partition of
> {1, .., n} grows much quicker then the possible sets of
> sticks for a given n.
For the probabilistic method to have plausibility, we need to also
consider the average number of partitions that correspond to the same
set of sticks. I have not seen this analysis carried out, nor do I
know how to do it. Statements about the apparent amount of "freedom"
may not extend to large problems.
Dan Hoey
Hoey@AIC.NRL.Navy.Mil
---
Newsgroups: sci.math, alt.radio.networks.npr, alt.usage.english
Followup-To: alt.radio.networks.npr
From: hoey@aic.nrl.navy.mil (Dan Hoey)
Date: 1995/09/27
Subject: Exponential misuse
On National Public Radio's program "Morning Edition" for 27 September,
there was a listener's letter chiding the news writers for misusing
the term "exponential". Apparently they had used the term to describe
a rise in the United Nations workforce from 3000 to 5000. The
listener stated that this was an arithmetic increase, because an
exponential increase would have to be at least from a number to its
square: from 3000 to 9 million.
The colloquial misuse of mathematical terms (and "exponential" in
particular) is so widespread and egregious that it is disappointing
to hear such a blatantly spurious "correction". (For the benefit of
the confused, the mathematical term "exponential" refers to a function
that grows by the same multiplicative factor over every like interval.
Thus a workforce that increases by 67 per cent each time period, as
above, would indeed be exponential. A looser, but well-established,
technical usage includes functions that are in bounded proportion to
strict exponentials, such as a workforce that falls 1000 short of
doubling each time period, also consistent with the above data.)
Of course, the term has colloquially come to mean simply "rapidly
growing", so the entire issue is moot in the context of a broadcast
to a general audience.
Unfortunately, I didn't catch the details of the letter, so I'd
appreciate hearing from anyone who recalls the period of time over
which the UN workforce increased, or the exact numbers used (3000
and 5000 are my best recollection), or any other specifics of the
situation.
Please respond by e-mail to Hoey@AIC.NRL.Navy.Mil; I'll summarize if
there is interest. Thank you.
Dan Hoey
Hoey@AIC.NRL.Navy.Mil
---
Newsgroups: alt.radio.networks.npr
From: hoey@aic.nrl.navy.mil (Dan Hoey)
Date: 1995/09/30
Subject: Re: Mistake in 'Cyber Angel' story
jkwes...@email.unc.edu (Keith Weston) writes:
> Please read my posts fully and don't pull bits out of context....
I have read your posts fully. I don't think it is out of context to
quote you as saying
> While all the information put forth in a series of these posts is
> correct (e.g. what .gif and .(j)peg stand for, etc.), it appears
> that some folks heard the report with half an ear. The angel said
> (approximately) that in chat rooms on services the term ".gif, as in
> 'got any .gifs' is a code word for pornography"....
To the extent to which "gif" or "jpeg" is a code word, it is a code
word for "pictures", which in turn, in some contexts, may imply
pornography. If the angel had said that, it would have been right.
If the angel said what you quoted "approximately", it would have been
merely misleading. But what I have been told is that the angel said
that "gif" referred to pictures of girls, and "jpeg" referred to
pictures of youths--that the two terms were used to distinguish two
kinds of different subject matter. And that is just completely wrong.
And if I have the story right, then your above summary indicates that
it is _you_ who have been listening with half an ear, and paraphrasing
out of context, and you should stop chiding other people for such
failings.
Dan
Hoey@AIC.NRL.Navy.Mil
---
Newsgroups: comp.theory
From: hoey@itd.itd.nrl.navy.mil (Dan Hoey)
Date: 1995/10/08
Subject: Re: P != NP!?
zu...@cs.cornell.edu (Zulfikar Amin Ramzan) writes:
>...I heard recently that someone has claimed
>to have proven that P != NP....
Ed Nelson of Princeton has a preliminary proof, which survived vetting
by some good mathematicians. I understand he proved the stronger
result that the polynomial hierarchy does not collapse.
(Sigma^p_(k+1) > Sigma^p_k for all k).
There is supposed to be a seminar on this starting Monday, as was
mentioned in sci.math. I expect further information will appear there
later in the week.
Dan Hoey [ posted and e-mailed ]
Hoey@AIC.NRL.Navy.Mil
---
Newsgroups: sci.math
From: hoey@pooh.tec.army.mil (Dan Hoey)
Date: 1995/10/08
Subject: Re: Game Strategy
: whi...@mail.powerup.com.au wrote:
: > "Two players, in turn, take balls out of two boxes. At any one move, each
: > of the players can take an arbitrary non-zero number of balls that is less
: > than 11 from any of the boxes, but only from one of the boxes. The winner
: > is the player who takes the last ball or balls. Show that the starting
: > player can always win if one of the boxes contains 100 balls and the other
: > 83."
Procedure for playing a normal impartial game:
1. Learn to play Nim.
2. Learn to convert any normal impartial game to Nim.
It's harder for misere play in some cases, but not this one.
: > I have developed a strategy for one box: firstly take enough balls from a
: > box to leave it with a multiple of 11, and then for after each turn, make
: > sure the box contains a multiple of 11 (a 'safe' move).
Jonathan E. Hardis (jhar...@tcs.wap.org) wrote:
: 11? Here's a hint. At the end of the game, one of the boxes must be
: empty, and the other must contain 12 balls. The rules are that your
: opponent must take out between 1 and 11 balls, not zero.
Here's another hint: if you read the post you're responding to, you
might not look so ridiculous. Players remove between 1 and 10 balls,
not 11. Whitby's one-box strategy is correct.
Dan Hoey [posted and mailed]
Hoey@AIC.NRL.Navy.Mil
---
Newsgroups: comp.theory
From: hoey@aic.nrl.navy.mil (Dan Hoey)
Date: 1995/10/09
Subject: Re: Why people say Quick-sort is the fastest sorting?
t...@kwi.com (Tom Howland) writes:
> It doesn't matter _what_ programming language you use, quick-sort
> does (on a good day, with the wind behind it) more comparisons than
> merge sort, by quite a large margin....
[ Followed by criticism of quicksort measurements (irrelevant to this
statement) and a pile of prolog code (for which I cannot detect any
purpose). ]
As a reader of comp.theory, I find the quoted statement to be
disappointingly ill-specified and completely unsupported. If you have
any reason to believe this statement, surely you can quantify what you
meant by it, and sketch or cite a proof. Otherwise, I must consider
it an act of intellectual dishonesty for you to promulgate it.
Dan Hoey [posted and e-mailed]
Hoey@AIC.NRL.Navy.Mil
---
Article 24409 of rec.arts.sf.fandom:
From: hoey@aic.nrl.navy.mil (Dan Hoey)
Newsgroups: rec.arts.sf.fandom
Subject: Re: Leeper Intersection report
Date: 11 Oct 1995 21:06:23 GMT
Organization: Navy Center for Artificial Intelligence
To: ian@soren.demon.co.uk (Ian Sorensen)
X-Distribution-Methods: posted and e-mailed
In-reply-to: ian@soren.demon.co.uk's message of Mon, 09 Oct 1995 21:59:57 +0100
ian@soren.demon.co.uk (Ian Sorensen) commments on Evelyn Leeper's remark:
> ``I looked through the Pocket Programme, which is in a small loose-leaf
> binder for no really good reason'' - if you read page 2 of it you would
> have found out the reason: it was so that you could remove pages you
> didn't want to carry about and add new ones that you did want! Your later
> complaint about it being too big is a common one at all cons, so the
> removable pages made it at least lighter if not smaller.
When I read that bit in the pocket program, I assumed it had to be one
of those British witticisms bypassing my ken. I certainly couldn't
take it seriously. The cover of the looseleaf binder alone, when
empty, was larger than all of the pages. Both in width and length (of
course) but also in thickness, due to the binding mechanism. It was a
neat idea, but it turned out considerably less convenient than if
you'd stapled or glued the pages together. And while I have a lot of
appreciation for your efforts in arranging it, I'll have to rate the
loose leaf notebook as an experiment that showed us how not to do it.
I just hope the Wizards of the Coast paid enough to make it
profitable, because the adverts were annoyingly numerous. They would
have been my choice, if I were going to go removing pages, but you
craftily printed them with indispensable information on the back. Oh,
well, at least it wasn't Bridge Publications this time.
> OK, sorry to pick on you and all that but, if you are going to post
> 27,000 words about an event you should at least try to make your
> criticisms reasonable and consistent.
Hmm. How long have you been reading fannish convention reportage? I
think you need to recalibrate your expectations. As a genre, about
the best you can say about fan journalism is that it's usually
somewhat fairer and more accurate than the Glasgow newspapers.
Dan Hoey Thieves! Ninety quid and they didn't
Hoey@AIC.NRL.Navy.Mil have a single Next Generation star!
---
Date: Wed, 11 Oct 95 22:56:15 -0400 (EDT)
From: Dan Hoey
To: Cube Lovers
Subject: Re: Using 5 Generators
I certainly agree that confirming minimality is an important result.
Thanks, Jerry.
But I can report that my search found 16 unique (*not* unique up to
conjugacy) half-way positions. I use the term "half-way" advisedly.
The "half-way" positions are 9q from Start and 8q from B or vice
versa. I guess you could say that the vice versa gives you a total
of 32=16+16 half-way positions, but the whole concept of "half-way"
is pretty slippery in this case anyway.
If I understand this, there are 16 positions at 9q from Start and 8q
from B, and there are 16 other positions at 8q from Start 9q from B.
Is each of the first bunch adjacent to exactly one of the other? And
vice versa? It would be good to get them reduced by Q2-conjugacy, as
well.
[in Q2]
> The four rotations are i, b, bb, and bbb, where we use lower case
> letters to simulate Frey and Singmaster's script notation for rotations.
> For example, b is the whole cube rotation consisting of grasping
> the Back face and rotating the whole cube (not just the Back face)
> clockwise by 90 degrees.
The reflections are similarly rrv, rrbv, ttv, and ttbv, where t and r
are the whole-cube rotations by the Top and Right faces, and v is the
central inversion.
Dan Hoey
Hoey@AIC.NRL.Navy.Mil
---
Newsgroups: rec.puzzles
Followup-To: rec.puzzles
From: hoey@aic.nrl.navy.mil (Dan Hoey)
Date: 1995/10/29
Subject: Re: 4x4x4 Cube (Rubiks Revenge) Solution?
m9390...@student.anu.edu.au writes:
> Is anyone ever released a mothod/solution for returning the 4x4x4
> Rubik's cube back to its pristine state?
Minh Thai wrote a booklet entitled "The Winning Solution to Rubik's
Revenge" that was published in 1982. I never went though his method,
but I noticed he counted the number of positions wrong by a factor of
two. Anyway, it's out of print now.
At any rate, it's easy, if laborious, to solve it using commutators.
See J. A. Eidswick's article in the March, 1986 American Math Monthly.
Dan Hoey Posted and e-mailed. No follow-ups from persons
Hoey@AIC.NRL.Navy.Mil who refuse to accept e-mail comments, please.
---
Article 34863 of rec.puzzles:
From: hoey@aic.nrl.navy.mil (Dan Hoey)
Newsgroups: rec.puzzles
Subject: Another Tetris puzzle
Date: 29 Oct 1995 06:22:27 GMT
Organization: Navy Center for Artificial Intelligence
Another interesting phenomenon in Tetris is the creation of
unsupported parts--parts that hang in the air without falling, because
their former support has cleared after they were stopped. For
instance, it is possible to create the following formation with only
six pieces:
.........x
x.........
x.........
x.........
The distance between the unsupported square and the nearest neighbor
is clearly at a maximum here. But how far away can you put an
unsupported part if you are restricted to using T-pieces? What about
the other pieces?
Are there any other measures of difficulty for unsupported parts,
bettter than distance to nearest neighbor?
Dan Hoey No follow-ups from persons who refuse
Hoey@AIC.NRL.Navy.Mil to accept e-mail comments, please.
---
Newsgroups: news.admin.net-abuse.misc
From: hoey@aic.nrl.navy.mil (Dan Hoey)
Date: 1995/10/30
Subject: Re: E-Mail SPAM from info.oaktreex.com...
Sam.Wil...@ed.ac.uk (Sam Wilson) writes:
> ... INETUSA have replied with an exemplary
> form letter describing their reponsese to spamming; I have heard
> nothing (unsurprisingliy?) from oaktreex.com.
Exemplary? The only thing exemplary about INETUSA's form letter was
that it was an instructive example of a half-hearted attempt to act
concerned without saying anything about whether they plan to do
anything about the current situation (or even read the complaints):
* They promised to react to spam originating "at the INETUSA.COM
machines". They didn't say whether they consider OAKTREEX.COM to be
such a machine.
* They claim that after a second offense from "the same account",
they will "revoke the posting privileges of that site". Aside from
the unspecified distinction between an "account" and a "site", this
says nothing about e-mail bombing, which is the problem under
discussion.
* They claim that in the case of SPAM that "passes through" their
facilities, there is little they can do. My point is that they can
at least stop supporting this nuisance with DNS service. And if,
as I suspect, they are the sole connection of OAKTREEX.COM, they
can just pull the plug.
* They mention that "INETUSA does not consider itself a Police Force
of the Internet." But I certainly didn't write anything suggesting
they might be. I just want to know when they are going to cease
being the Internet Pumping Station for the Internet Sewage Outfall.
* They thank me for bringing this to their attention and promise to
"address it accordingly." Uh huh.
When the same OAKTREEX scumbunny junk-mailed the same nuisance ad ten
days ago, postmas...@INETUSA.COM promised "The user will be deleted
from my service and will not be allowed access to my domains". (Does
anyone have any idea what that is supposed to mean?) Now they are
managing to be EVEN MORE vague and dissembling about their plans.
It's time.
Either it's time for an explanation of why INETUSA.COM didn't fix this
when they said they would, and how INETUSA.COM plans to prevent any
future occurrence,
Or it's time to start finding out why UUNET is supplying gateway
service to a service that acts as a front for junk emailers.
Tell us, INETUSA, what time is it?
Dan Hoey posted and emailed
Hoey@AIC.NRL.Navy.Mil
---
Newsgroups: news.admin.net-abuse.misc
From: hoey@aic.nrl.navy.mil (Dan Hoey)
Date: 1995/10/31
Subject: Re: Don't buy from JEM Computers! (TS061489)
Stephen Sharpley writes:
> re Ivan Reid's comments, I complained to the postmaster at uunet and
> I have just received received a response setting out their SPAM code
> of practice - the implication is that jembargains have been cut off.
Really? Did you get the same response Ivan later got and posted?
::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
: To Whom It May Concern,
:
: UUNET Technologies appreciates your notifying us of a SPAM incident.
:
: Our current SPAM policy is as follows:
:
: If the offender's message originated at a UUNET customer site, the
: customer will be warned. A second offense originating from the same
: account will force UUNET to revoke the posting privileges of that site.
:
: If the SPAM is passing through UUNET's facilities, there is little that we
: can do.
:
: UUNET does not consider itself a Police Force of the Internet. We care
: nothing of the content of any message, SPAM or otherwise. However, we do
: care about maintaining Internet etiquette. We will cut off, if possible,
: any SPAM site that we carry as a customer.
:
: Thank you again for bringing this to our attention. We will address it
: accordingly.
:
: Thank you,
: --
: Anthony Charles Williams, Jr
: UUNET Technologies Inc.
: Mail: h...@uunet.uu.net
: uunet!help
: Phone: (800) 900-0241
: (703) 206-5440
: FAX: (703) 206-5993
::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
Oddly enough, this is nearly identical to the message that I received
from INETUSA.COM about the junk email from Oaktreex selling computer
parts. I complained the non-responsiveness of that policy yesterday.
The differences in UUNET's message mitigate some of my complaints.
But there is still the major problem that this is a form letter about
_Usenet_ spam, and the only remedy they propose (should they decide
this is an abuse, which is not specified above) is to "revoke the
posting privileges" of a site. They say nothing about removing email
service from a junk e-mailer.
And contrary to Stephen's message, I see no implication that
"jembargains have been cut off." I would very much like to have
clarified what UUNET has done or proposes to do about JEM Computers.
Dan Hoey
Hoey@AIC.NRL.Navy.Mil posted and emailed
---
Newsgroups: rec.puzzles, alt.radio.networks.npr
Followup-To: rec.puzzles
From: hoey@pooh.tec.army.mil (Dan Hoey)
Date: 1995/11/08
Subject: Re: WE puzzle for 11-5-95 (spoiler)
Richard Renner writes:
: Solution to 10-29-95 NPR puzzle with Will Shortz.
: Draw a five-by-five box, that is, it has 25 squares. Remove the
: four corner squares to leave 21 squares. How many squares or
: rectangles of any size can you find in this figure?
[ long solution clipped ]
It's good to see you provide an explanatory solution for this
problem--it's much more informative than a computer program. But for
this one there's an easier way of demonstrating the answer.
A rectangle can be specified by the subset of the columns it occupies
and the subset of the rows it occupies; conversely, any nonempty
contiguous subsets of rows and columnns intersect in a rectangle. If
we did not remove the corners of the box, there would be fifteen
contiguous subsets in each direction, for 225 rectangles. How many
rectangles should we subtract from this number to account for removing
the box's corners? There are 64 rectangles from the that original box
that include one of the removed corners (four corners times width
{1,2,3,4} times length {1,2,3,4}), sixteen rectangles that include two
of the removed corners (four sides times width {1,2,3,4}), and one
rectangle that includes all four of the removed corners. So the
answer is 225-64-16-1=144.
Obpuzzle 1: Is it only coincidence that the numbers above are all
squares, or is there a deeper reason?
Obpuzzle 2: The squares of the mutilated box we used above have 32
corner points in all:
. . . .
. . . . . .
. . . . . .
. . . . . .
. . . . . .
. . . .
How many rectangles can be drawn that take exactly three of their
vertices from among these points?
Dan Hoey No followups from persons who refuse
Hoey@AIC.NRL.Navy.Mil to accept e-mailed comments, please.
---
Newsgroups: rec.puzzles
From: hoey@aic.nrl.navy.mil (Dan Hoey)
Date: 1995/11/16
Subject: Counting rectangles (Spoiler) (was Re: WE puzzle for 11-5-95)
I posed:
> Obpuzzle 2: The squares of the mutilated box we used above have 32
> corner points in all:
> . . . .
> . . . . . .
> . . . . . .
> . . . . . .
> . . . . . .
> . . . .
> How many rectangles can be drawn that take exactly three of their
> vertices from among these points?
Last chance to do it yourself....
This is a somewhat harder counting problem, but not that hard. For
nomenclature, we consider the 32 given "points" plus the four missing
"corners" to form the "bounding box". When counting the rectangles,
we refer to the vertex that is not one of the 32 points as "the fourth
vertex".
First consider the rectangles with vertical and horizontal sides.
Such a rectangle cannot extend outside the bounding box (for it would
then have another vertex outside). So the fourth vertex must be one
of the missing corners (chosen in four ways) and the height and width
of the rectangle can then be independently chosen from {1,2,3,4}, for
64 rectangles.
If the rectangle has oblique sides, we first observe that the fourth
vertex will lie on a point with integer coordinates--this can be seen
in several ways, say by looking at the equal and parallel sides of the
rectangle. Now, the fourth vertex cannot be one of the missing
corners, for then at least one of its adjacent vertices would lie
outside the bounding box. So the fourth vertex must lie outside the
bounding box. We will count the number of rectangles with exactly
three vertices in the bounding box, then adjust the count to include
rectangles that have a corner as a vertex.
Because its adjacent vertices lie within the bounding box, the fourth
vertex must be exactly one of above, below, to the left, or to the
right of the bounding box--we will assume below, and multiply our
results by four. Consider the horizontal and vertical distances from
the fourth vertex to its adjacent vertices:
. . . .
. . 2 . . .
--- 1 . . . . .
^
| . . . . . .
|
b . . . . . . |
| v
| . . . 3 ---
v d
--- 4 ---
^
|<--a-->|<--c-->| |
The sides are perpendicular, so a/b = d/c. For vertices 1 and 3 to
lie in the bounding box, we must have a+c <= 5, and there will be
6-a-c possible horizontal placements that will keep 1 and 3 inside the
bounding box. In order that 1 and 3 lie within the bounding box and 4
lies below, there are min(b,d) possible vertical placements.
Now consider the adjustment for the missing corners. If b>d there is
one forbidden position that has point 3 on the missing corner. If d>b
there is a forbidden position with point 1 on the missing corner. If
d=b there are two forbidden positions unless a+c=5, in which case
there is only one forbidden position that has both points on missing
corners.
So I set up the following table of possibilities. If (a,b,c,d) is a
case, then (c,d,a,b) is also such a case (unless a=b=c=d, when they
are the same case). I list the one with b>a, or if a=b then the one
with c>a. Since a+b <= 5, we need only consider a/b among
{1,1/2,1/3,1/4,2/3}.
Column H is the number of horizontal placements, column V the number
of vertical placements, and F is the number of forbidden placements
with a vertex on a corner. M is the multiplicity--4 if a=b=c=d, 8
otherwise. The total column shows (H V - F) M.
a/b : a b c d : H V : F M :Total
: : : :
1 : 1 1 1 1 : 4 1 : 2 4 : 8
: 1 1 2 2 : 3 1 : 1 8 : 16
: 1 1 3 3 : 2 1 : 1 8 : 8
: 1 1 4 4 : 1 1 : 1 8 : 0
: 2 2 2 2 : 2 2 : 2 4 : 8
: 2 2 3 3 : 1 2 : 1 8 : 8
: : : :
1/2 : 1 2 2 1 : 3 1 : 1 8 : 16
: 1 2 4 2 : 1 2 : 1 8 : 8
: 2 4 2 1 : 2 1 : 1 8 : 8
: : : :
1/3 : 1 3 3 1 : 2 1 : 1 8 : 8
: : : :
1/4 : 1 4 4 1 : 1 1 : 1 8 : 0
: : : :
2/3 : 2 3 3 2 : 1 2 : 1 8 : 8
----
Total oblique rectangles 96
Orthogonal rectangles (from above) 64
----
Answer 160
This analysis was sufficiently complicated that I also wrote a
computer program to enumerate the rectangles, which produced the same
answer.
ObPuzzle: There's got to be an easier way, please!
Dan Hoey
Hoey@AIC.NRL.Navy.Mil
---
Article 35815 of rec.puzzles:
From: hoey@aic.nrl.navy.mil (Dan Hoey)
Newsgroups: rec.puzzles
Subject: Re: Palendromes
Followup-To: poster
Date: 17 Nov 1995 00:16:29 GMT
Organization: Navy Center for Artificial Intelligence
Reply-To: archive-request@questrel.com
To: armathis@expert.cc.purdue.edu (Andrew Mathis),"brian odom"
In-reply-to: "brian odom"'s message of Wed, 15 Nov 1995 10:23:02 -0500 (EST)
armathis@expert.cc.purdue.edu (Andrew Mathis) asked:
>I think about a month back I read an article in
>this group from someone about Palyendromes:
Make up your mind how you're going to misspell "palindrome".
>...This particular article contained a copy of an longer form of the
>Panama palendrome...
"brian odom" wrote:
> uh, what palindrome are you looking for?
> could it be this familiar one?
> "doc, note, i dissent. a fast never prevents a fatness. i diet on cod."
No, he's almost certainly looking for the 548-word one I discovered in
1984, with the help of a program I wrote. It's in the archive (with a
bunch of others), so there's no need to repost it. Just send e-mail
to archive-request@questrel.com with a message that reads
send palindromes
You can include the line "return_address your_name@your_site.your_domain"
if the return address in your headers is wrong.
I've tried to set it up so that you can send e-mail to archive-request
by replying to this message. If you want to write to me, use the
address in my signature.
Dan Hoey posted and emailed
Hoey@AIC.NRL.Navy.Mil
---
Newsgroups: sci.math.research
From: hoey@aic.nrl.navy.mil (Dan Hoey)
Date: 1995/11/18
Subject: Re: Sociable Chains
r...@ix.netcom.com (Robert G. Wilson v)
> The function, Sum of the proper Divisors, or the Sum of the
> Aliquiont parts of X, is a well known Number Theory arithmetic
> function...
Guy, in _Unsolved Problems in Number Theory, 2nd edition_[1994],
calls the cycles "aliquot cycles". (I've never seen the spelling
"aliquiont", though my dictionary says "aliquant" is a word for a
non-divisor!? Mercifully, they both seem to be obsolete except in
this usage). Perfect numbers, sociable pairs, aliquot cycles.
> I understand that a sociable of cycle 3 exists....
Unless you've heard very recently, no cycles of length 3, 7, or >9
are known, save for one cycle of length 28 beginning at 14316, found
by Poulet. "It has been conjectured that there are no 3-cycles.
On the other hand it has been conjectured that for each k there
are infinitely many k-cycles."
Dan Hoey [posted and emailed]
Hoey@AIC.NRL.Navy.Mil
---
Article 35876 of rec.puzzles:
From: hoey@aic.nrl.navy.mil (Dan Hoey)
Newsgroups: rec.puzzles
Subject: Re: Addition Problem
Date: 18 Nov 1995 23:52:23 GMT
Organization: Navy Center for Artificial Intelligence
Distribution: world
In-reply-to: "Stephen H. Landrum"'s message of Thu, 16 Nov 1995 09:58:02 -0800
yair@ashur.cc.biu.ac.il (Yair Elharrar) poses the knapsack problem:
> > >A set S of N integers is given, all in the range 1 to L.
> > >another integer T is given. find a subset A so that the sum of
> > >all the numbers in A is equal to T.
and requests a "polynomial" solution.
karr@cs.cornell.edu (David Karr) notes that the problem is NP-complete.
So there are a number of ways. You could program a nondeterministic
machine to recognize solvable instances of such problems in polynomial
time. But I suppose nondeterministic machines are right out, since
they are sufficiently nonrealistic models of computation that they are
useful only for theoretical investigation. (Anyone who is tempted to
confuse this sort of nondeterminism with quantum uncertainty, please
dont.)
Or you could solve it on any old machine in polynomial space. But you
of course wanted a polynomial _time_ solution, which you should state.
Polynomials are just these functions, they don't care what you bound
with them.
Or you could notice that the knapsack problem is only "weakly"
NP-complete. In this case, that means that if you require that the
integer T be given in "unary notation" (as a string of T ones) then
your program will run slower, but it will run in polynomial time! The
trick, of course, is that we are talking about time that is a
polynomial in the size of the input, and representing T in unary
increases the size of the input much, much more than it slows down the
program.
But if you want to solve it by proving P=NP, Karr writes:
> > (On the other hand, since most CS theoreticians believe P is not =
> > NP, I wouldn't bet on solving the problem that way.)
I don't believe that opinion has any mathematical basis, and I am not
convinced it is even a majority. Personally, I tend to believe that
we will not find any polynomial algorithms for NP-hard problems, nor
prove P < NP. But I have no opinion on P =? NP.
slandrum@3do.com (Stephen H. Landrum) writes:
> Ralph Merkle developed an encryption scheme based on the knapsack
> problem, and its supposed NP-completeness. His encryption scheme
> was cracked, which I believe means that the knapsack problem is in
> fact not NP-complete.
No, it means that Merkle-Hellman was based on a sub-complete special
case of the knapsack problem. It had to be restricted in such a way
that messages could be easily decoded with special information (the
secret encryption key). It turns out that the modification also
allowed decoding without the key--i.e., it was a restriction to a
class of easy cases of knapsack. But general knapsack has its hard
cases, and it is those that make it NP-complete.
Dan
Hoey@AIC.NRL.Navy.Mil
---
Newsgroups: rec.arts.books
From: hoey@aic.nrl.navy.mil (Dan Hoey)
Date: 1995/11/19
Subject: She Who Must Be Obeyed
A few months ago in another newsgroup, I mentioned the phrase ``She
Who Must Be Obeyed,'' attributing it to H. Rider Haggard (_She_,
1887). I was thanked by a reader who was sick of hearing the phrase
attributed to John Mortimer, whose fictional character Rumpole thus
refers to his wife. I had to admit that though my primary experience
with the phrase agrees with the _Oxford Dictionary of Quotations_'s
attribution to Haggard, I have no real certainty that he originated
that form of address.
Today I read in ``Rumpole and the Quacks'' (_Rumpole a la Carte_,
Penguin, 1990, p. 164) a passage in which Rumpole mentions
``She Who Must Be Obeyed, whose title, as you will know, derives
from the legendary and all-powerful Queen Cleopatra...'.'
Could Mortimer be mistaken? Possible, of course, but quite surprising.
Could Rumpole be mistaken? But Rumpole is no Bertie Wooster, and
usually gets his stuff right.
Could Rumpole be _kidding_ us? He's an inveterate leg-puller, but I
don't see the point of this one.
Could Cleopatra really be the original object of the phrase? The more
I think, it looks like Haggard's S.W.M.B.O., Ayesha, owes a great deal
of her character to Cleopatra, but did the phrase really predate Haggard?
I would greatly appreciate any assistance in tracking down answers to
these questions. Please choose e-mail or public response based on the
degree of public interest--I'll certainly summarize any e-mailed
information for anyone who is curious.
Dan Hoey
Hoey@AIC.NRL.Navy.Mil
---
Newsgroups: sci.math
From: hoey@aic.nrl.navy.mil (Dan Hoey)
Date: 1995/11/25
Subject: Re: Number sequences problem
rklei...@moe.coe.uga.edu (Ronen Kleiner M) asks:
> Take any four real numbers, a1,b1,c1,d1.
> Define an ("a sub n")=abs(a(n-1) - b(n-1)), bn=abs(b(n-1)-c(n-1)),
> cn=abs(c(n-1)-d(n-1)) and dn=abs(d(n-1)-a(n-1)). ["abs"=absolute value].
and asks if iteration of this process eventually reaches {0,0,0,0}.
The answer is no.
The polynomial x^3 + x^2 + x - 1 has one real root, near 0.543689, or
exactly
( (3 sqrt(33)+17)^(1/3) - (3 sqrt(33)-17)^(1/3) - 1 ) / 3.
The sequence {x,1,(2x-1)/x,(1-x-x^2)/x} ~ {0.543689,1,0.160713,0.295598}
does not terminate. It maps to
{1-x, (1-x)/x, (2-3x-x^2)/x, (1+x)(2x-1)/x};
the longevity is not affected when we multiply each element by
x/(1-x), to get
{x, 1, (2-3x-x^2)/(1-x), (1+x)(2x-1)/(1-x) }
which differs from the original sequence by
{0, 0, (1-x-x^2-x^3)/(x(1-x)), -(1-x-x^2-x^3)/(x(1-x))}.
But these terms are all zero, by the definition of x.
I wonder if this is the only eigenvector of the system (up to rotation
and scaling)? Are there higher-order cycles? Is there any literature
on this process?
Dan
Hoey@AIC.NRL.Navy.Mil
---
Newsgroups: sci.math
From: hoey@aic.nrl.navy.mil (Dan Hoey)
Date: 1995/11/29
Subject: Generating Rubik's Cube
About generating the cube's group with arbitrary elements of that
group, mscho...@Math.RWTH-Aachen.DE (Martin Schoenert) writes:
> ... Rubik's cube can be generated by 2 elements.
> Moreover almost any random pair of elements will do the trick....
Actually, I think it's more accurate to say that a random pair of
elements has nearly a 75% probability of generating the cube. At
least, I'm pretty sure that's an upper bound, and I don't see any
reason why it shouldn't be fairly tight. That's for the group where
the whole cube's spatial orientation is irrelevant. I think it's more
like 56% (9/16) if you also need to generate the 24 possible
permutations of face centers.
About the minimal presentation of the cube group on the usual generators,
frb6...@cs.rit.edu (Frank R Bernhart) writes:
> The answers may be in SINGMASTER, et.al.
> "Handbook of Cubic Math" or BANDEMEISTER (sp?) "Beyond R. Cube"
I recall Singmaster wanted to know if anyone found a reasonably-sized
presentation; I don't know if any have been found in the intervening
fifteen years. The best I know of is a few thousand relations, some
of them several thousand letters long. I've been meaning to try
chopping that down a bit.
Dan posted and e-mailed
Hoey@AIC.NRL.Navy.Mil
---
Date: Wed, 29 Nov 95 12:14:40 -0500 (EST)
From: Dan Hoey
To: Cube Lovers
Subject: Generating Rubik's Cube
About generating the cube's group with arbitrary elements of that
group, mschoene@Math.RWTH-Aachen.DE (Martin Schoenert) writes:
... Rubik's cube can be generated by 2 elements.
Moreover almost any random pair of elements will do the trick....
Actually, I think it's more accurate to say that a random pair of
elements has nearly a 75% probability of generating the cube. At
least, I'm pretty sure that's an upper bound, and I don't see any
reason why it shouldn't be fairly tight. That's for the group where
the whole cube's spatial orientation is irrelevant. I think it's
more like 56% (9/16) if you also need to generate the 24 possible
permutations of face centers.
About the minimal presentation of the cube group on the usual
generators, frb6006@cs.rit.edu (Frank R Bernhart) writes:
The answers may be in SINGMASTER, et.al.
"Handbook of Cubic Math" or BANDEMEISTER (sp?) "Beyond R. Cube"
I recall Singmaster wanted to know if anyone found a reasonably-sized
presentation; I don't know if any have been found in the intervening
fifteen years. The best I know of is a few thousand relations, some
of them several thousand letters long. I've been meaning to try
chopping that down a bit.
Dan posted and e-mailed
Hoey@AIC.NRL.Navy.Mil
---
Article 36326 of rec.puzzles:
From: hoey@aic.nrl.navy.mil (Dan Hoey)
Newsgroups: comp.theory.cell-automata,rec.puzzles
Subject: Re: Smallest dying "life" group?
Followup-To: comp.theory.cell-automata
Date: 01 Dec 1995 22:43:47 GMT
Organization: Navy Center for Artificial Intelligence
Distribution: inet
In-reply-to: wft@math.canterbury.ac.nz's message of 28 Nov 1995 23:17:45 GMT
To: wft@math.canterbury.ac.nz (Bill Taylor)
wft@math.canterbury.ac.nz (Bill Taylor) asked for the smallest dying
group in Conway's Life, specifying
> ... a group of stones that completely dies with no progeny, in one
> generation. To exclude trivia it must include at least one stone that
> dies by overcrowding.
I also exclude non-minimal groups--groups that contain a nontrivial
dying group as a proper subset.
Bill gives the population-9 and -10 examples
. . x . . . . . x .
. . x . . x . x . . . . x x . .
x x x x x . x x x . x x x x x x
. . x . . . . x . x . . x x . .
. . x . . . x . . .
and asks for anything else of population 10 or less. A
disappointingly large number of duplicate and incorrect examples were
posted....
I wrote a program to search for minimal examples. There are no other
groups of population 9, and only the three population-10 groups:
. . . x . x . . . x . x . . . x . x
. . x . . . x . x . . . x . x . . .
x x x x x . . x x x x . . x x x x .
. . x . . . . . x . . . . . x . . .
. . x . . . . . x . . . . x . . . .
You may consider these to be inessential modifications of the first
two above, but that's all there are.
Similar inessential modifications yield the three minimal
population-11 groups:
. . . . x . x . . . x . x . . x x . x
. . . x . . . . . x . . . x x x x x .
. x x x x x . x x x x x . . . x x . .
. . . x . . . . . x . . . . . . . . x
x . x . . . . . . . x . x
It is not until population 12 that we see the significantly new form
(in three variants)
. . . x . . . . . x . . . . . x . .
. . . x . . . . . x . . . . . x . .
. . x x x x x . x x x x x . x x x .
x x x x . . . x x x . . . x x x . x
. . x . . . . . x . . . . . x . . .
. . x . . . . . x . . . . . x . . .
in addition to four more modifications of the population-9 and -10
examples.
Dan Hoey posted and e-mailed
Hoey@AIC.NRL.Navy.Mil
---
Newsgroups: rec.puzzles
From: hoey@aic.nrl.navy.mil (Dan Hoey)
Date: 1995/12/02
Subject: Re: Floating Prism Problem[Spoiler?]
About the orientation of floating objects
> du...@JSP.UMontreal.CA (DUBE Danny) writes:
> >My criterion was that the mass center of the block must be the lowest
> >possible. [...]
David A. Karr (k...@cs.cornell.edu) notes that this is not the
correct criterion. Jim Saxe noted, when solving the
analogous problem for a square last year, the criterion that
the "energy" of the configuration is minimized, where
the energy is the vertical distance between the square's
"center of gravity" [which is identical to its geometrical
center] and its center of buoyancy [which is the center of
gravity of the submerged portion].
I can't verify this criterion, except to note that 1) this
criterion has given reasonable-looking results in the cases
I've looked at, and 2) Jim is just about always right about
these things.
Given that we never got a definitive answer on a cube floats,
it seems overambitious to debate the much hairier problem of
floating prisms (being less symmetric and possessing an extra
degree of freedom). Perhaps someone should figure out how
regular tetrahedra of various densities float. And anyone
mentioning surface tension should be sent home.
Dan
Hoey@AIC.NRL.Navy.Mil
---
Newsgroups: sci.math
From: hoey@pooh.tec.army.mil (Dan Hoey)
Date: 1995/12/03
Subject: Re: Putnam spoilers -- Bean Problem
Brian David Rothbach writes:
> You're right, reducing the 3 bean pile to 2 beans wins. The simple
> stategy is just don't reduce any 4 bean piles to 3 beans....
> Most complicated is if you take 1 bean from the four bean piles....
> Of course, I miscalculated this last case on my test.
This problem is completely uncomplicated if you apply Sprague-Grundy
theory, turning each pile of beans into a nim-heap:
2-piles can move only to 0, so they act like nim-heaps of size 1;
3-piles move to 2-piles (nim 1) or to 0, so they act like
nim-heaps of size 2;
4-piles can't move to any 0-heap, so they act like 0-heaps;
5-piles move only to a 0-heap, so they act like 1-heaps; and
n-piles, n>5 act like n-2-piles, or (n mod 2)-heaps.
The winning move from any position is to move so that there are an
even number of 2-heaps (3-piles) and an even number of 1-heaps
(2 or 5,7,9,... piles). This is possible unless you already are in
such a position, in which case you have lost.
I'm surprised they didn't at least pose the game in its misere
variant, where some analysis of the special role of 3-piles seems to
be necessary. I think then the strategy is to play the normal game as
long as there are at least two piles greater than 2, and thereafter to
move to positions with an odd number of 2-piles (and no others).
Dan
Hoey@AIC.NRL.Navy.MIl
---
Article 36349 of rec.puzzles:
From: hoey@aic.nrl.navy.mil (Dan Hoey)
Newsgroups: rec.puzzles
Subject: Re: Vanishing Leprechaun
Date: 03 Dec 1995 05:08:16 GMT
Organization: Navy Center for Artificial Intelligence
To: stevejs@skypoint.com (Steve Schwartz)
stevejs@skypoint.com (Steve Schwartz) writes:
> The "Vanishing Leprechaun" is a novelty that shows 15 leprechauns.
> When you rearrange two of the three pieces, one of the leprechauns
> has disappeared -- there are now only 14. The puzzle is a variation of
> the old Sam Lloyd "Get Off The Earth" puzzle.
There's a photograph of the puzzle in Martin Gardner's _aha! Gotcha:
Paradoxes to puzzle and delight_ [WH Freeman, 1982]. He writes:
The funniest versions of these paradoxes are those in which a
drawing of a person is caused to disappear. Consider, for
example, The Vanishing Leprechaun Puzzle, drawn by Pat Patterson
of Toronto, copyrighted [1968] and sold by the Elliott Company of
Toronto. The puzzle is reproduced below. To avoid damaging the
book, photocopy it, then cut the border and along the dotted lines
to make three rectangles. Switch the top rectangles, and one of
the fifteen leprechauns disappears without a trace....
> I need to find out where I can locate and buy several of these things.
> Years ago, they were made by a company in Toronto, but that isn't true
> any longer.
It's too bad Elliott isn't selling them any more. You could of course
photocopy them out of Gardner, but the photo is pretty fuzzy. In case
a bare outline of the problem will do, you can use:
.......................................................
: xx : xx :
: xx xx : xx xx :
: xx xx : xx xx xx xx :
: xx xx xx : xx xx xx xx :
: xx xx xx xx : xx xx xx xx xx xx :
: xx xx xx xx : xx xx xx xx xx xx xx :
:..xx.xx.xx....xx.xx.:..xx.xx.xx....xx.xx....xx.xx.xx.:
: xx xx xx xx xx xx xx xx xx xx xx xx xx xx :
: xx xx xx xx xx xx xx xx xx xx xx xx :
: xx xx xx xx xx xx xx xx xx xx :
: xx xx xx xx xx xx xx xx :
: xx xx xx xx xx xx :
: xx xx xx xx :
: xx xx :
:.....................................................:
Dan Hoey posted and e-mailed
Hoey@AIC.NRL.Navy.Mil
---
Date: Sun, 03 Dec 95 14:46:30 -0500 (EST)
From: Dan Hoey
To: Cube Lovers
Subject: Re: Generating Rubik's Cube
On the probability that two random elements will generate the entire
cube group, I wrote:
... a random pair of elements has nearly a 75% probability of
generating the cube. At least, I'm pretty sure that's an upper
bound, and I don't see any reason why it shouldn't be fairly tight.
That's for the group where the whole cube's spatial orientation is
irrelevant. I think it's more like 56% (9/16) if you also need to
generate the 24 possible permutations of face centers.
I can now answer the spatial orientation part of the question, and
it's much lower. We're talking about C, the 24-element group of
proper motions of the whole cube. If we select two elements at random
with replacement, the probability is only 3/8 that they will generate
the whole group.
The kinds of motions that can take part in a generating pair are a
90-degree rotation about an axis, a 120-degree rotation about a major
diagonal, and a 180-degree rotation about a minor diagonal. Note that
the last kind fixes two major diagonals and an axis. Two motions
generate C iff they are
(48 ways) a 120 and a 180, unless they fix the same major diagonal,
(48 ways) a 180 and a 90, unless they fix the same axis,
(24 ways) two 90s at right angles, or
(96 ways) a 90 and a 120.
The number comes out so even I suspect there's something deeper going
on than the exhaustive analysis I used.
As for generating the (fixed-face) Rubik's group, I still suspect that
two elements almost always generate the entire group unless they are
both even. Anyone who has a Sims's-algorithm implementation handy
could help out with a Monte-carlo approximation to see if this is
approximately right. Or, I wonder, is there a way of getting an exact
number, perhaps with the help of GAP?
Dan posted and e-mailed
Hoey@AIC.NRL.Navy.Mil
---
Article 36371 of rec.puzzles:
From: hoey@aic.nrl.navy.mil (Dan Hoey)
Newsgroups: rec.puzzles
Subject: Re: ASK MARILYN
Date: 04 Dec 1995 06:12:20 GMT
Organization: Navy Center for Artificial Intelligence
In-reply-to: wtc@cs.utexas.edu's message of 1 Dec 1995 08:13:49 -0600
wtc@cs.utexas.edu (Wichaya Top Changwatchai) writes:
> As I understand it, Marilyn vos Savant's claim to fame is that she has the
> highest IQ test score submitted to the Guinness Book of World Records....
I've heard the test that distinguishes her score from those of other
expert test-takers was one she had a hand in developing or
administering, at least in an earlier version. It's amusing to
speculate whether this experience gave her an advantage in taking the
test.
> Perhaps it's best to think of her as an advice columnist with a penchant for
> puzzles.
... who fancies herself an expert in mathematics.
... who takes pride in her opposition to the "mathematical establishment".
... who was obviously out of her depth in writing a book that tried
to explain Andrew Wiles's proof of Fermat's Last Theorem.
... who nonetheless made up a spurious theory that Wiles's proof was not
applicable to FLT because of its use of "hyperbolic geometry".
... who has never explained how she came to the mistaken belief that
there was any use of hyperbolic geometry in that proof.
Perhaps if she goes on making grade-school level mathematical errors,
the public may come to understand how incompetent she is to critique
serious mathematics. If ever a fraud deserved deflation, she's it.
Dan Hoey
Hoey@AIC.NRL.Navy.Mil
---
Newsgroups: news.admin.net-abuse.misc
From: hoey@aic.nrl.navy.mil (Dan Hoey)
Date: 1995/12/05
Subject: Email spam from RichKahn@InterRamp.com, big surprise
Apparently the interramp bozos have decided the Usenet spam isn't
getting out, so they're sending it e-mail. Someone's research
indicates I'm interested in their long-distance scam? Sure....
Dan Hoey
Hoey@AIC.NRL.Navy.Mil
================================================================
From: "Richard K. Kahn"
Date: Mon, 4 Dec 1995 22:34:12 +0000
Subject: Making Internet History!
Reply-To: RichK...@interramp.com
Our research indicates that this material is of interest to you. If
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================================================================
---
Article 36601 of rec.puzzles:
From: hoey@pooh.tec.army.mil (Dan Hoey)
Newsgroups: rec.puzzles
Subject: Re: Dense plane-coverings in Conway's "life".
Date: 7 Dec 1995 23:40:40 GMT
Organization: Naval Research Laboratory, Washington, DC
Bill Taylor (wft@math.canterbury.ac.nz) wrote:
: I'm interested in finding regular patterns in Conway's "life",
: that cover the plain as densely as possible.
: What are the greatest densities achievable -
: (i) with a time-periodic pattern, preferably stationary;
The cute name for a period-1 pattern is a "still life". It seems 1/2
is the greatest possible density. Noam Elkies outlined a proof
approach for the stronger result that no pattern of maximum adjacency
degree 3 can have density over 1/2. I'm not sure he's polished it
into a complete proof yet. Here are some density-1/2 still-lifes,
mostly from Noam and earlier sources.
Chicken wire
. x x x x . . . . x x x x . . x x . . x x . .
. x . . x . x x . x . . x x x . . x x . . x x
. x . . x . x x . x . . x . . x x . . x x . .
. x x x x . . . . x x x x x x . . x x . . x x
x . . . . x x x x . . . . . . x x . . x x . .
x . x x . x . . x . x x . x x . . x x . . x x
x . x x . x . . x . x x . . . x x . . x x . .
x . . . . x x x x . . . . x x . . x x . . x x
x x . . x x x x . . x x x x x x . x x x x . x x x x
. x . x . . . x . x . . x . . x . x . . x . x . . x
x . . x x x x . . x x x x . . x . x . . x . x . . x
. x x . . . . x x . . . x x x x . x x x x . x x x x
x . . x x x x . . x x x . . . . x . . . . x . . . .
. x . x . . . x . x . . . x x . x . x x . x . x x .
x x . . x x x x . . x x . x x . x . x x . x . x x .
. . x x . . . . x x . . . . . . x . . . . x . . . .
x x x x . x x x x . x x x x
. . . . x . . . . x . . . . x x . . x . x . . x . x . . x
x x x x . x x x x . x x x x . x . . x . x . . x . x . . x
x . . x . x . . x . x . . x . x x x x . x x x x . x x x x
x . x . . x . x . . x . x . . . . . . x . . . . x . . . .
x . x x x x . x x x x . x x x . x x . x . x x . x . x x .
. x . . . . x . . . . x . . . . x x . x . x x . x . x x .
. x . x x . x . x x . x . x x . . . . x . . . . x . . . .
. x . x x . x . x x . x . x x
. x . . . . x . . . . x . . .
x . x x x x . x x x x . x x x x x x x . x x x x .
x . x . . x . x . . x . x . . . . . . x . . . . x
. . x . x . . x . x . . x . x . x x . x . x x . x
x x x . x x x x . x x x x . x . x . x x . x . x x
. x . . . . x . . .
x . x x x x . x x x
x x x x x x x x . . . . . . . . x . x . . x . x . .
x . . . . . . x . x x x x x x . x . x . . x . x . .
x . x x x x . x . x . . . . x . x . x x x x . x x x
x . x . . x . x . x . x x . x . . x . . . . x . . .
x . x . . x . x . x . x x . x . . x . x x . x . x x
x . x x x x . x . x . . . . x . x x . x . x x . x .
x . . . . . . x . x x x x x x . . . . x . . . . x .
x x x x x x x x . . . . . . . . x x x . x x x x . x
. . . . . . . . x x x x x x x x
. x x x x x x . x . . . . . . x
. x . . . . x . x . x x x x . x x x x x . . x x x x . .
. x . x x . x . x . x . . x . x x . . . x . x . . . x .
. x . x x . x . x . x . . x . x . x x x x . . x x x x .
. x . . . . x . x . x x x x . x . x . . . x . x . . . x
. x x x x x x . x . . . . . . x . . x x x x . . x x x x
. . . . . . . . x x x x x x x x x . x . . . x . x . . .
: (ii) that preferably contains no groups of live cells infinite in extent.
Well, the above qualify, but my favorite still life (because it's my
own invention) is the following:
. . . x x x x x x x x x x
. . . . . . . . . x
x x x x x x x x . x
x . . . . . . x . x
x . x x x x . x . x
x . x . . x . x . x
x . x . . x . x . x
x . x . x x . x . x
x . x . x . . x . x
x . x . x . . x . x
x . x . x x x x . x
x . x . . . . . . x
x . x x x x x x x x
x . . . . . . . . .
x x x x x x x x x x . . .
Not only does it have an infinite connected group, it _is_ an infinite
connected group. Rich Schroeppel has shown that there is no finite
connected still-life other than the 2x2 block, but this can be
modified by adding spirals to make uncountably many infinite connected
still-lifes. I don't know if there's any i.c.s-l. that is not made up
of such spirals, though. Could there be one that has lacunae?
Dan Posted and e-mailed
Hoey@AIC.NRL.Navy.Mil
---
Newsgroups: rec.puzzles
From: hoey@pooh.tec.army.mil (Dan Hoey)
Date: 1995/12/08
Subject: Re: ASK MARILYN
Jamie Dreier (pl436...@brownvm.brown.edu) wrote:
: The classic sort of game theoretic analysis doesn't generally go by
: maximizing minimum *expected* payoffs, but we can certainly extend the
: idea here.
That's quite a bizarre thing to say, since the subject known as "Game
Theory" consists almost entirely of analysis of how to maximize the
minimum expected payoff of imperfect-knowledge games. The analysis of
perfect-knowledge games has had to content itself with other names.
I've seen three books on the subject (_The Compleat Strategist_, some
Dover title like _Analysis of Games of Strategy_, and a recent course
text that looked promising). I suspect there are dozens of books and
hundreds of research papers.
: But now the question is, what is the relevance of this maximin? Is there
: any reason to suppose it is the 'best' move in any sense? I can't see any
: reason whatsoever....
It's at least _a_ criterion for best move, and it gives you the best
possible guarantee of your chance of winning a car. I do not know of
any other criterion that is not maximizing the minimum expected payoff
over some distribution--the only disagreement I have seen is over what
distribution has been specified. Do you have a different criterion to
propose that maximizes some other measure of goodness?
: Maximin strategies are important in very, very limited contexts, I think.
I think not. I think some other things about that statement, which I
will forbear to mention.
The usual context is when you are in a zero-sum game, so you should
plan for the case when your opponent will minimize your payoff. It
turns out that many games (such as this) have a _stable_ strategy,
such that you cannot increase the payoff if your opponent plays the
stable strategy, and your opponent cannot decrease your payoff if you
play the stable strategy.
Another context is in artifically-constructed problems, where you are
asked to provide an answer that does not rely on information that was
not provided in the problem statement. If the answer requires
maximizing your expectation over an unknown probability distribution,
you may not have any better option than to maximize over the
worst-case distribution. Solving the problem for a fixed distribution
that you assert to have been intended is not usually considered
responsive.
The subject of artificially-constructed problems is by far the more
limited context, being mostly concerned with puzzles constructed for
recreational or instructive purposes. But limited as that context may
be, you have found it.
Dan
Hoey@AIC.NRL.Navy.Mil
---
Newsgroups: rec.puzzles
From: hoey@aic.nrl.navy.mil (Dan Hoey)
Date: 1995/12/09
Subject: Re: ASK MARILYN
jud.mccra...@swsbbs.com (JUD MCCRANIE) partially quotes the problem
posed in M vos Savant's column, which read in full:
"Suppose you're on a game show, and you're given a choice of three
doors. Behind one door is a car; behind the others, goats. You
pick a door--say, No.1--and the host, who knows what's behind the
doors, opens another door--say, No.3--which has a goat. He then
says to you, 'Do you want to pick door No.2?' Is it to your
advantage to switch your choice?"
> I believe that it is implied that the choice is always offered.
> (I believe that was the way it was done on the TV show).
I quoted it in full to make it clear that no such implication is
expressed in the problem statement. As for the way it is done on the
TV show, I do not recall seeing any situation like this on the show,
and I've heard reports of interviews in which Monty Hall said that
such straightforward re-dealing was never done. So there seems to be
no precedent on the TV show to support such an implication.
> Sure, it is sloppily written, and is not a precise enough statement
> of the problem, but when I first read it years ago my interpretation
> was that he always offered you the chance to change.
Perhaps you read a different problem years ago, and are allowing your
recollection of it to color your perception of this one. As I weary
of pointing out, there are two distinct problems, the "classic" one in
which the host is required to offer a choice and the "common" one in
which the host is not required to offer a choice. I really can't see
why anyone who realizes and understands the difference would classify
this one as the former.
Dan Hoey posted and e-mailed
Hoey@AIC.NRL.Navy.Mil
---
Newsgroups: rec.puzzles
From: hoey@pooh.tec.army.mil (Dan Hoey)
Date: 1995/12/09
Subject: Re: Geoboard squares [spoiler]
Bill Graham (Bill_Gra...@cmug-la.org) wrote:
: Geoboards are often used in elementary schools. They are usually
: plastic with protruding pegs in a square grid. You can loop rubber
: bands around the pegs to make various shapes.... How many squares
: can be formed by using the dots as the vertices (corners) of the
: squares?
I answered this a few years back, but I don't think it's in the
archives. Perhaps that is because I am unwilling for my writing to
be used without attribution.
On the n x n board, consider k in {2,3,...,n}. There are (n-k+1)^2
ways of placing a k x k square with edges parallel to the edges of
the board. Consider the 4(k-1) pegs that form the perimeter of such
a square. Any set of four pegs equally spaced around the perimeter
forms the corners of a square, making k-1 squares formed by those
pegs. Conversely, given any square formed by pegs on the board, take
the smallest containing square with edges parallel to the edges of the
board; the given square will have its corners evenly spaced around the
periphery of the containing square. So we count all squares in this
way.
We want the sum, for k in {2,3,...,n}, of (k-1)(n-k+1)^2. Let
t=n-k+1; this is the sum, for t in {1,2,...,n-1}, of
t^2(n-t) = nt^2 - t^3.
My handy table of Bernoulli polynomials tells me that the sum for t in
{1,...,n-1} of t^2 is n(n-1)(2n-1)/6 and the sum for t in {1,...,n-1}
of t^3 is n^2(n-1)^2/4.
So the answer is n^2(n-1)(2n-1)/6 - n^2(n-1)^2/4 = n^2 (n^2 - 1) / 12.
For n=4 this is 20; for n=5 this is 50.
Nobody answered the ObPuzzles:
Easy: How many equilateral triangles are formed by a triangular array
of side n? How many regular hexagons in a hexagonally-shaped
triangular array of side n?
Hard: How many cubes are formed by a three-dimensional cube with n
points on an edge.
Dan Hoey posted and e-mailed
Hoey@AIC.NRL.Navy.Mil
---
Newsgroups: rec.puzzles
From: hoey@aic.nrl.navy.mil (Dan Hoey)
Date: 1995/12/10
Subject: Re: Checkerboard Problem [more spoilers]
Roland Curit asks how many paths there are
from one corner of a checkerboard to the opposite corner, using edges
of the squares. A path may cross itself but may not reuse an edge.
Thanks to Roland for an interesting problem and to Jim Gillogly for
showing it worthy of attack (or at least of a bit of weekend hacking).
Jim found there were over a billion paths through the 5x5
checkerboard, resorting to a program that used Zobrist hashing (I've
never studied Zobrism) because the simple recursive search got too
long to wait for. Using a different approach, I got results that
agree with and extend Jim's; the results for squares are:
1x1 . . . . . . 2
2x2 . . . . . . 16
3x3 . . . . . 800
4x4 . . . . 323632
5x5 . . . 1086297184
6x6 . . 30766606427588
7x7 7466577706821521924
I also have a large number of results for rectangles. The remainder of
this message is a longish description of the method.
I decided that for a hairy combinatoric problem like this, I would do
better to search with combs. A "comb" is a term I use to describe a
structure on the integers {0,..,n}. A comb is a disjoint family of
subsets of {0,..,n} containing one singleton and arbitrarily many
pairs.
I work with what I call "toothed checkerboards"--checkerboards that
have an extra set of edges (teeth) added along the right side. For
instance, here is a 3x4 toothed checkerboard. We number the teeth
from 0 to n (top to bottom).
*---+---+---+---+---* tooth 0
| | | | |
+---+---+---+---+---* tooth 1
| | | | |
+---+---+---+---+---* tooth 2
| | | | |
+---+---+---+---+---* tooth 3
A path system (PS) on a toothed checkerboard is a set of
nonoverlapping paths along the edges of the toothed checkerboard in
which exactly one path has an endpoint in the upper-left corner of the
checkerboard, and all other endpoints are at the ends of the teeth.
For instance, here is a PS on a 5x5 toothed checkerboard.
corner *---------------\ /---* Tooth 0
| |
' /-------\ \---/ '
| |
' | ' | ' /---* Tooth 2
| | |
/--/ /--\ \------/ /--* Tooth 3
| | | |
| | \-----------+---* Tooth 4
| | |
\---/ ' ' ' \---* Tooth 5
There are three paths in this PS, from the corner to the tooth 0, from
tooth 2 to tooth 4, and from tooth 3 to tooth 5.
A comb on {0,...,n} is said to "represent" a PS on an n-by-m toothed
checkerboard when
1. the singleton of the comb contains the tooth-number of the
endpoint of the path starting in the corner,
2. the pairs of the comb are the tooth-numbers of the endpoints of
the other paths in the PS.
For instance, comb {{0},{2,4},{3,5}} represents the 5x5 PS above.
It should be clear that each PS is represented by exactly one comb.
So to count PSs, we count the number represented by each comb, and add
them up. The reason this helps is that combs capture the essential
features necessary for extending an n-by-m PS into an n-by-(m+1) PS.
This is done by finding the "successors" of each comb, in the sense
that the {{0},{2,4},{3,5}} above is the successor of comb {{1},{3,4}},
which represents the above PS restricted to the 5x4 toothed
checkerboard. Note that a comb can be the successor of another in
more than one way, corresponding to multiple ways of extending a PS.
So what I construct is a matrix of nonnegative integers, indicating
the multiplicity of the successor relation. Exercise: Find the other
way of extending a {{1},{3,4}} PS into a {{0},{2,4},{3,5}} PS.
A final touch is to be able to tell when a PS can be extended to a
path through an entire checkerboard. This is done by connecting
adjacent tooth endpoints of the paths in numerical increasing pairs,
with the largest endpoint connected to the corner. If the result is a
single path, that is the unique way to extend the n-by-m PS into a
n-by-(m+1) checkerboard path. Note that in the example, by connecting
tooth 0 to 2 and 3 to 4, we arrive at a path through the 5x6
checkerboard. It is straightforward to translate this criterion into
a condition on the representative comb.
So I wrote a program to count these paths by comb. The number of
combs for various heights of checkerboard are:
height #combs height #combs height #combs
0 1 4 50 8 6876
1 2 5 156 9 26200
2 6 6 532 10 104456
3 16 7 1856
Which grows superexponentially, but not as badly as factorially.
Generating the transition matrix, though, takes a considerable amount
of time using a naive recursive search--there may be a better way of
calculating transitions. A more pressing problem is the size of the
transition matrix, which is the main reason I haven't got results for
8x8. But this should be within the range of PC-class machines if you
take care to avoid running out of primary memory.
Dan
Hoey@AIC.NRL.Navy.Mil
---
Newsgroups: rec.puzzles
From: hoey@aic.nrl.navy.mil (Dan Hoey)
Date: 1995/12/10
Subject: Re: Checkerboard Problem [more spoilers]
Here is the table of solutions from my last message, extended to the
8x8 checkerboard.
1x1 . . . . . . . . 2
2x2 . . . . . . . . 16
3x3 . . . . . . . 800
4x4 . . . . . . 323632
5x5 . . . . . 1086297184
6x6 . . . . 30766606427588
7x7 . . 7466577706821521924
8x8 15681997226277809235573754
Anyone who missed that message may request a copy by e-mail.
Dan posted and e-mailed
Hoey@AIC.NRL.Navy.Mil
---
Date: Sun, 17 Dec 95 02:41:02 -0500 (EST)
From: Dan Hoey
To: Cube Lovers
Subject: Presenting Rubik's Cube
A few weeks ago I mentioned the old problem of finding a presentation
of the Rubik's cube group in terms of the usual generators. This was
posed by Singmaster over 15 years ago, and as far as I know has never
been addressed. I've made some progress.
I work using a specially selected set of generators, rather than the
usual generators given for the cube. First I give presentations
separately for the permutation groups of the corners and edges, and
the orientation groups of the corners and edges. Then I join the
permutation groups with their respective orientation groups to
form the wreath groups, which describe the possible motions of the
respective piece types. I join the two wreath groups in such a way
that the permutation parity of the two is equal. Finally, I discuss a
method of converting to the usual generators.
In Coxeter and Moser's _Generators and Relations for Discrete Groups,
2nd ed_ I found Coxeter's presentation 6.271 for the symmetric group
on {1,2,...,n}, n even. With a modest change of variables, his
presentation is on generators
v=(1 2) and s=(2 3 ... n) ((1))
and relators
v^2,
v s^(n-2) (v s^-1)^(n-1),
(s^-1 v s v)^3, and
((s^-1 v)^i (s v)^i)^2, i=2,...,n/2-1. ((2))
Here n will be 8 or 12 to present the group of the permutations of
corners or edges, respectively.
The orientation group of the corners (or edges) is the direct product
of n-1 cyclic groups, which can be presented with generators
r_0=(1)+(2)-
r_1=(1)+(3)-, ...,
r_(n-2)=(1)+(n)-, ((3))
where (k)+ indicates a reorientation of piece k in place and (k)-
indicates the inverse reorientation. The relators here are
r_i^d, (d=3 (corners) or 2 (edges)), and
r_i r_j r_i^-1 r_j^-1, 0 <= i < j <= n-2. ((4))
I generate the wreath group with the union of the generators ((1,3)).
The added relators
v r_0 v r_0
v r_i v r_0 r_i i=1,...,n-2,
s^-1 r_i s^i r_(i+1)^-1 i=0,...,n-3, and
s^-1 r_(n-2) s^i r_0^-1 ((5))
will permit moving the r_i to the end of a word, after which the
previous relators ((2)) and ((4)) may be used to manipulate the parts
separately, just as a Rubik's cube solvers can perform any needed
permutations before reorientations.
In the wreath group, the r_i are conjugate to each other. The third
line of ((5)) may be used to define r_k = s^-k r_0 s^k, so I eliminate
r_1,...,r_(n-1) and write r_0 as r. The last line of ((5)) is then a
consequence of s^(n-1)=e, which is implied by ((2)), according to
Coxeter. The conjugacy also lets me rewrite ((4)) as
r^d, (d=3 (corners) or 2 (edges)), and
s^-j r s^j r' s^-j r' s^j r, j=1,...,(n-2)/2. ((6))
As the discussion turns to working with corners and edges together, I
write cs,cr and es,er for the respective generators. I use a single
generator v that acts on both corners and edges, to ensure that the
corner permutation has the same parity as the edge permutation. Since
any identity in {v,cs,cr} must use an even number of v's, the identity
will hold in the when the v operates on edges as well; similarly for
{v,es,er} operating on the corners.
To present the whole cube group, I use all five generators, relators
((2,5,6)) for both corners and edges, and new relators
es cs es' cs', er cs er cs', es cr es' cr', er cr er cr'
to make the two kinds of generators commute, so they may be separated
in a word. According to GAP, the complete set of relators is
er^2,
v^2,
cr^3,
er cr er cr^-1,
er cs er cs^-1,
es cr es^-1 cr^-1,
es cs es^-1 cs^-1,
(v cr)^2,
(v er)^2,
cr cs cr cs^-1 cr^-1 cs cr^-1 cs^-1,
(er es er es^-1)^2,
cs cr^-1 cs^-1 v cs cr cs^-1 v cr,
cs^-1 cr^-1 cs v cs^-1 cr cs v cr,
(es er es^-1 v)^2 er,
(es^-1 er es v)^2 er,
cr cs^2 cr cs^-2 cr^-1 cs^2 cr^-1 cs^-2,
(cs^-1 v cs v)^3,
(er es^2 er es^-2)^2,
(es^-1 v es v)^3,
cr^-1 cs^-2 v cs^2 cr cs^-2 v cr cs^2,
cr^-1 cs^2 v cs^-2 cr cs^2 v cr cs^-2,
er es^-2 v es^2 er es^-2 v er es^2,
er es^2 v es^-2 er es^2 v er es^-2,
cr cs^3 cr cs^-3 cr^-1 cs^3 cr^-1 cs^-3,
((cs^-1 v)^2 (cs v)^2)^2,
(er es^3 er es^-3)^2,
((es^-1 v)^2 (es v)^2)^2,
cs^-3 v cs^3 cr cs^-3 v cr cs^3 cr^-1,
cs^3 v cs^-3 cr cs^3 v cr cs^-3 cr^-1,
(es^3 er es^-3 v)^2 er,
(es^-3 er es^3 v)^2 er,
(cs^-2 v cs^-1 v cs v cs^2 v)^2,
(es^-2 v es^-1 v es v es^2 v)^2,
(er es^4 er es^-4)^2,
(es^-4 er es^4 v)^2 er,
(es^4 er es^-4 v)^2 er,
v cs^6 (v cs^-1)^7,
(es^-3 v es^-1 v es v es^3 v)^2,
(er es^5 er es^-5)^2,
(es^5 er es^-5 v)^2 er,
(es^-5 er es^5 v)^2 er,
(es^4 v es^-4 v es^-1 v es v)^2,
v es^10 (v es^-1)^11, ((7))
which has 43 relators of total length 597. It is apparently beyond
GAP's ability to verify that these relators present the cube group,
though I have verified some smaller wreath groups.
This presentation is of course in terms of generators {v,es,er,cs,cr},
not the generators {F,B,L,R,T,D} natural to the cube. But they can be
translated as follows. Each quarter-turn Q can be expressed as a word
w(Q) over {v,es,er,cs,cr}, and adding the relators
F' w(F), B' w(B), L' w(L), R' w(R), T' w(T), D' w(D) ((8))
will create a presentation on eleven generators
{v,es,er,cs,cr,F,B,L,R,T,D}. I estimate that the added relators will
be under 70 letters each, and probably less. If it is desired to
completely eliminate {v,es,er,cs,cr}, that may be done by replacing
each of {v,es,er,cs,cr} with processes in terms of F,B,L,R,T,D,
throughout ((7,8)). My understanding of the current state of the
software is that the processes will probably be less than 30
quarter-turns each. This would yield a presentation of 49 relators
and perhaps 2000 letters. It should be possible to improve this quite
a bit. I would suggest:
1. Choosing the corner and edge numbering to reduce the
rewriting blowup,
2. Allowing w(Q) to use previously-related Q's as well as
{v,es,er,cs,cr}.
3. Adding new relators to abbreviate higher powers, especially
of es and cs, in the presentation.
4. Introducing short relators such as F^4=FBF'B'=e to cut down on
the general verbosity of the relators.
But improvement to the level of actual comprehensibility may require
new ideas. Perhaps Dave Rusin's "clearer statement" of the question
may help, if I can figure out what it means.
Dan posted and e-mailed
Hoey@AIC.NRL.Navy.Mil
---
Date: Sun, 17 Dec 95 02:47:46 -0500 (EST)
From: Dan Hoey
To: Cube Lovers
Subject: Re: Presenting Rubik's Cube
For the benefit of Cube-Lovers, here is rusin@washington.math.niu.edu
(Dave Rusin)'s remark on finding a presentation of Rubik's cube.
You have a group Rubik generated by the 6 90-degree rotations g_i.
Let F be the free group on 6 generators x_i and f: F --> Rubik the
obvious homomorphism. There is a big kernel N of f. (It is actually
a free group: subgroups of free groups are free). You wish to find
the smallest (free) subgroup K of N such that N is the normal closure
of K in F. (When you give a presentation of Rubik in the form
Rubik = ,
you are implicitly describing K as the subgroup of F generated by the
corresponding words in the x_i.)
To give this process at least a chance of success, you abelianize it:
Let N_ab be the free abelian group N/[N,N], so that there is a natural
map from N into N_ab. Since N is normal in F and [N,N] is
characteristic in N, the action of F by conjugation on N lifts to an
action of F on N_ab; even better, the subgroup N < F acts trivially
on N_ab, so that F/N (i.e., the Rubik group itself) acts on N_ab.
We think of N_ab as a Rubik-module (or better, as a Z[Rubik]-module).
The subgroup K < N also maps to a subgroup K[N,N]/[N,N] of N_ab;
significantly, N is the F-closure of K iff N=[K,F]K so that N_ab
is generated as a Z[Rubik]-module by F.
Thus, the question of what constitutes a minimal set of
relations is the same as asking for the number of generators needed for
a certain Rubik-module. (Of course, while you're at it, you might as
well ask for a whole presentation or resolution of the Rubik-module.
Inevitably, you will be led to questions of group cohomology.)
He also included GAP's help file on the cube, which I think has been
posted here already.
Dan
Hoey@AIC.NRL.Navy.Mil
---
Date: Sun, 17 Dec 95 03:12:30 -0500 (EST)
From: Dan Hoey
To: Cube Lovers
Subject: Re: Million dollar cube
Jerry Bryan wonders about the 15th anniversary celebration:
That would make it 1980. Is that right? I think Cube-Lovers started in
1980, but I have just been reading some early stuff from Singmaster dated
1978 and 1979.
In _Rubik's Cubic Compendium_, Erno Rubik remarks that his major
insight occurred in 1974. He patented the cube in January, 1975 and
it went on sale in Hungary in 1977.
In 1980, one million were sold in Hungary, and U.S. distribution
through Ideal began. Incidentally, they were always the "Magic Cube"
until Ideal renamed them.
There is some more information in the archives about Bela Szalai
(Logical Games, Inc), who sold the white-faced cubes in the U.S.
after seeing the cube in Hungary in 1978. I'm not sure whether he
actually beat Ideal to the ship date, or what happened to him after
the big cube bust.
Dan
Hoey@AIC.NRL.Navy.Mil
---
Date: Sun, 17 Dec 95 21:11:35 -0500 (EST)
From: Dan Hoey
To: Cube Lovers
Subject: Re: Presenting Rubik's Cube
In my article on a presentation of the Rubik's cube group last night,
I omitted a relator from list ((7)):
v es v cs v es^-1 v cs^-1.
This brings the number of relators to 44, with a total length of 605.
Experiments with GAP on some smaller cube-like groups indicate that
with this addition, the presentation is correct.
My apologies for the error.
Dan Hoey Posted and e-mailed.
Hoey@AIC.NRL.Navy.Mil
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Newsgroups: sci.math
From: hoey@aic.nrl.navy.mil (Dan Hoey)
Date: 1995/12/18
Subject: Re: Presenting Rubik's Cube
In my article on a presentation of the Rubik's cube group last night,
I omitted a relator from list ((7)):
v es v cs v es^-1 v cs^-1.
This brings the number of relators to 44, with a total length of 605.
Experiments with GAP on some smaller cube-like groups indicate that
with this addition, the presentation is correct.
My apologies for the error.
Dan Hoey Posted and e-mailed.
Hoey@AIC.NRL.Navy.Mil
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