From: Siraaj Khandkar <siraaj@khandkar.net>
Date: Mon, 30 Nov 2020 11:00:17 +0000 (-0500)
Subject: Add info on seeds
X-Git-Url: https://git.xandkar.net/?a=commitdiff_plain;h=a5bb74bccb064e856bde4b33656a3fe71141aabc;p=cellular-automata.git

Add info on seeds
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diff --git a/seeds/README.md b/seeds/README.md
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+Seeds
+=====
+
+https://en.wikipedia.org/wiki/Seeds_(cellular_automaton)
+
+> Seeds is a cellular automaton in the same family as the Game of Life,
+> initially investigated by Brian Silverman[1][2] and named by Mirek
+> Wójtowicz.[1][3] It consists of infinite two-dimensional grid of cells, each
+> of which may be in one of two states: on or off. Each cell is considered to
+> have eight neighbors (Moore neighborhood), as in Life. In each time step, a
+> cell turns on or is "born" if it was off or "dead" but had exactly two
+> neighbors that were on; all other cells turn off. Thus, in the notation
+> describing the family of cellular automata containing Life, it is described
+> by the rule B2/S.[1]
+>
+> In Game of Life terminology, a pattern in which all cells that were on turn
+> off at each step is called a phoenix. All patterns in Seeds have this form.
+> Even though all live cells are constantly dying, the small birth requirement
+> of two cells means that nearly every pattern in Seeds explodes into a chaotic
+> mess that grows to cover the entire universe. Thus, in Wolfram's
+> classification of cellular automata, it is a Class III automaton, in which
+> nearly all patterns evolve chaotically.[1]
+>
+> However, some patterns are known to behave in a more controlled fashion,
+> repeating the same shape either in the same position of the grid (an
+> oscillator) or translated some number of grid units after several steps (a
+> spaceship). More complex rake and puffer patterns are known which move like
+> spaceships leaving trails of oscillators or other spaceships behind them.
+> Most of these patterns move at a speed of 1 cell per time step (the so-called
+> speed of light, or c/1)[4] including three commonly seen spaceships with four
+> on cells each, but slower-moving patterns are also known. A collection of
+> patterns for the Seeds rule collected by Jason Summers includes patterns
+> found by Stephen Wright, Mirek Wójtowicz, Noam Elkies, Mark Niemiec, Peter
+> Naszvadi, and David Eppstein.[5]