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From: victor@klipper.UUCP (L. Victor Allis)
Newsgroups: net.ai,net.philosophy
Subject: Re: A halting problem
Message-ID: <531@klipper.UUCP>
Date: Sun, 12-Jan-86 09:59:46 EST
Article-I.D.: klipper.531
Posted: Sun Jan 12 09:59:46 1986
Date-Received: Tue, 14-Jan-86 06:06:33 EST
References: <2175@aecom.UUCP>
Reply-To: victor@klipper.UUCP (L. Victor Allis)
Distribution: net
Organization: VU Informatica, Amsterdam
Lines: 31
Xref: watmath net.ai:3166 net.philosophy:3745

In article <2175@aecom.UUCP> berger@aecom.UUCP (Micha Berger) writes:
>	The human mind, on the other hand, given enough time an
>practice, can find an endless loop in any procedure. (You doubt this?)

Try this one.

I am very interested in a termination proof of the procedurecall
Fermat(1, 1, 1, 1) :

procedure Fermat(x, y, z, n : integer);
begin
  if power(x, n) + power(y, n) = power(z, n) then
    writeln('Eureka')
  else
    begin
      repeat
        AssignNextValues(x, y, z, n)
      until n > 2;
      Fermat(x, y, z, n)
    end
end;

where 'power' is a function returning the obvious, and AssignNextValues
is a function which takes four parameters and assigns the next four
values to these parameters with respect to some ordering of the set
of all ordered 4-tupels of natural numbers, which has a smallest element,
(1, 1, 1, 1) in that ordering.

L. Victor Allis
Free University of Amsterdam
The Netherlands.