Chapter 6: Starting from Randomness

Section 2: Four Classes of Behavior

2D class 4 cellular automata

No 5- or 9-neighbor totalistic rules nor 5-neighbor outer totalistic ones appear to yield class 4 behavior with a white background. But among 9-neighbor outer totalistic rules there are examples with codes 224 (Game of Life), 226, 4320 (sometimes called HighLife), 5344, 6248, 6752, 6754 and 8416, etc. It turns out that the simplest moving structures are the same in codes 224, 226 and 4320.

From Stephen Wolfram: A New Kind of Science [citation]