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- From: jwmills@moose.cs.indiana.edu (Jonathan Mills)
- Newsgroups: comp.theory.cell-automata
- Subject: Re: Crystals in Life
- Message-ID: <1992Sep14.135519.14524@news.cs.indiana.edu>
- Date: 14 Sep 92 18:55:13 GMT
- References: <1992Sep11.204742.107084@Cookie.secapl.com>
- Organization: Indiana University, Bloomington
- Lines: 29
-
- In article <1992Sep11.204742.107084@Cookie.secapl.com> frank@Cookie.secapl.com (Frank Adams) writes:
- >I have done some playing around with infinite stable patterns in Conway's
- >game of Life. I call such patterns crystals.
- >
- >(1) Has there been any investigation of this? A reference would be
- >appreciated.
-
- I did a study of crystals in 1988. I have an unpublished manuscript,
- maybe I should send it in! Most of the work was developing crystals
- and related objects: strings, ropes, fuses, crystal eaters, etc.
-
- I have thirty or forty crystals made from blinkers, ropes and other
- patterns. Some can be made into fuses that "burn," exploding other
- crystals. Detonation waves in crystals can be initiated by gliders.
- Some crystals can tolerate defects, other crystals are composites
- (I can't recall the terminology for this, sounds like tectite). The
- most interesting objects are crystal eaters that excrete stable
- patterns, transforming a dense pattern to a sparser pattern.
- The problem is to make the edge stable, which as I recall can be
- done with a toroidal space. But without the wrap the eaters tend
- to leave junk that wrecks the crystal excreta.
-
- >
- >(2) I would like to prove that no crystal can have a density greater than
- >1/2. 1/2 is easy to achieve; just fill space with the rectangle "O." (for
- >example). I can establish an upper bound of 6/11 easily enough, but I
- >haven't managed to do better.
-
- Sounds quite interesting. I never got that far.
-