Fast Simulation of Cellular Automata by Self-Composition

Computing the configuration of any one-dimensional cellular automaton at generation $n$ can be accelerated by constructing and running a composite rule with a radius proportional to $\log n$. The new automaton is the original one, but with its local rule function composed with itself. Consequently, the asymptotic time complexity to compute the configuration of generation $n$ is reduced from $O(n^2)$-time to $O(n^2\mathrm{/}\log n)$, but with $O(n^2\mathrm{/}(\log n{)}^3)$-space, demonstrating a time-memory tradeoff. Experimental results are given in the case of Rule 30.