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few of the 256 possible elementary rules. But for underlying rules that have more complex behavior—like rules 22, 30, or 110—it turns out that in the end it is always possible to emulate all 256 elementary rules.

The emulation here is, however, only for a single step. So the fact that it is possible does not immediately establish universality in any ordinary sense. But it does once again support the idea that almost any cellular automaton whose behavior seems to us complex can be made to do computations that are in a sense as sophisticated as one wants.

And this suggests that such cellular automata will in the end turn out to be universal—with the result that out of the 256 elementary rules one expects that perhaps as many as 27 will in fact be universal.

Captions on this page:

Summaries of how various underlying cellular automata do in emulating a single step in the evolution of each of the 256 possible elementary cellular automata using the scheme from the facing page with blocks of successively greater widths.

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