A Rule for Fast Computation and Analysis of Soliton Automata

Abstract

Cellular automata that exhibit soliton behavior are studied. A simple rule—the fast‐rule theorem (FRT)—is introduced, which allows immediate calculation of the evolution process. The FRT is suitable for the development of parallel algorithms, for the analysis and prediction of the behavior of the automata, and for hand calculation as well. The FRT consists of first selecting a finite set of sites and then obtaining the next state by simply inverting one bit in these sites, while leaving the remaining bits unchanged. This finite set can be detected by inspection. The distinction between single and multiple particles is made precise and shown to depend not only on the number of consecutive zeros separating particles but also on their position relative to the sites in the finite set mentioned above. Three applications are given. The first is a demonstration of the FRT as an analytical tool and settles the (up to now) open question of stability. The other two applications demonstrate the use of the FRT in the construction of a periodic particle and in obtaining soliton collisions by hand calculations.