Newsgroups: comp.theory.cell-automata
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From: rwg@RUSSIAN.SPA.Symbolics.COM (Bill Gosper)
Subject: Re: on Life (and Death)
Message-ID: <19910328224539.9.RWG@TSUNAMI.SPA.Symbolics.COM>
Sender: tytso@athena.mit.edu (Theodore Y. Ts'o)
Organization: The Internet
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Date: 28 Mar 91 22:45:00 GMT
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I've forwarded this to rcs@la.tis.com.

    Date: Thu, 28 Mar 1991 11:20-0500
    From: Allan C. Wechsler <ACW@YUKON.SCRC.Symbolics.COM>

	Date: Wed, 27 Mar 1991 12:51 EST
	From: Paul Crowley <aipdc@castle.edinburgh.ac.uk>

	What's the simplest known pattern that has no parent?

    Winning Ways p. 829 gives:

    xxxxxxxxxxxxxx xxxxxxxxxxxxxxxxxx
    x x x x x x xxxx xx xxx xxx xx xx
    xxxxxxxxxxxxx x x xxx xxx xxx xx
    x x x x x x xx xxxxx xxx xxx xxxx
     x x x x x x xxx x xxx xxx xx x x
    xxxxxxxxxxxxxx xxxx xxx xxx xxxxx
     x x x x x x xxx xxxx xxx xxx x x
    x x x x x x x x x xx xxx xxx x xx
    xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx

    I understand Schroeppel was in the group that discovered this; I don't
    know his net address but I've CC'd Gosper and perhaps he'd be willing to
    forward to Schroeppel our request to hear the story of this monster's
    discovery.

I think Roger Banks wrote the "ataviser" program, and some subset of Banks,
Schroeppel, Mike Speciner, and Mike Beeler "manually" guided a marathon
tree search.

About a year and a half ago, Schroeppel and Hickerson found a bunch of
patterns with very small predecessor counts.  These are used as modules
in existence proofs for GOE's within various rectangles, some quite cozy.
Rich should know the current record.