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From: dgc@ucla-cs.UUCP
Newsgroups: net.math
Subject: Re: Yet Another Puzzle
Message-ID: <960@ucla-cs.ARPA>
Date: Sat, 25-Aug-84 23:17:44 EDT
Article-I.D.: ucla-cs.960
Posted: Sat Aug 25 23:17:44 1984
Date-Received: Mon, 27-Aug-84 06:49:29 EDT
References: <313@othervax.UUCP>
Organization: UCLA CS Dept.
Lines: 28

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(Athens -- near Syracuse)

    What we have here is a problem one of my lecturers back in the good
    old days gave me:

	For ANY POSITIVE integer, call it i, will the following program
	ALWAYS stop?

	while (i is not 1) if (i is even) then i = i/2; else i = 3*i + 1;
	stop;

	We do of course assume that i can be arbitrarily large, etc.
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This is a famous old problem, usually known as the "Syracuse" problem.

It has been attributed to Stanislaus Ulam (of "Manhatten Project" fame).

It has been verified for extremely large values of i, using Crays' and
other reasonably fast computers.

Great glory will accrue to him (or her) who solves it (in other words,
it ain't easy!).

David G. Cantor

Arpa: dgc@ucla-locus.arpa
UUCP: {ihnp4, randvax, sdcrdcf, trwspp, ucbvax}!ucla-cs!dgc