To: WSFAlist at KeithLynch.net
Date: Mon, 1 Jan 2007 21:06:01 -0500
Subject: [WSFA] Re: Ex-presidents of the US
From: ronkean at juno.com
Reply-To: WSFA members <WSFAlist at KeithLynch.net>

On Mon, 1 Jan 2007 18:23:54 -0500 (EST) "Keith F. Lynch"
<kfl at KeithLynch.net> writes:

> There have been zero (ex-presidents alive) on six occasions:
>
> * Before April 30, 1789, when nobody had ever been president
> * From December 14, 1799 to March 4, 1801, when Adams was president
> * From July 31, 1875 to March 3, 1877, when Grant was president
> * From June 24, 1908 to March 4, 1909, when Roosevelt was president
> * From January 5, 1933 to March 4, 1933, when Hoover was president
> * From January 22, 1973 to August 4, 1974, when Nixon was president
>

Wouldn't the period before the inauguration of the second president
qualify as well as the period before the inauguration of the first
president?

> My first thought was that the number starts at zero, increases
> whenever a president leaves office without dying, and decreases
> when
> an ex-president dies.  But then I realized this wasn't quite right.
> Can you see the flaw?
>

Your first sentence there is a true statement, but it might not make a
complete basis for the appropriate algorithm, because an ex-president
might become president again.  When that happens, the question arises
whether that president is considered to be both an ex-president and a
sitting president at the same time, or temporarily loses his status as
living ex-president while he is a sitting president.  I would say that a
person could be both president and living ex-president at the same time,
in which case your original statement would be a proper basis for the
algorithm, but correct my reasoning if it is faulty.

> If there's any interest, I can easily modify my programs to do the
> same with any other list of people whose birth and death dates are
> known, or to list when they'd been dead twice as long as they'd
> been
> alive, or the midpoint of their life, or whatever.
>

A quibble - people are alive for up to about nine months before they are
born.

What programming language did you use, and how long did it take you to
write and debug the program?  How could one be sure that such a program
would always give the correct answer?

Ron Kean

.