| Abstract: | In this paper we address the problem of how to build a universal computer in an excitable medium. We construct a cellular automata model of a two-dimensional excitable medium (the 2 + medium) evolving in discrete time, with the following properties: every element of the medium has three states (rest, excited and refractory); an element interacts with the eight closest elements; an element in the rest state becomes excited only if exactly two of its eight neighbours are excited. To prove that the 2+ medium is a minimal cellular automata model of a physical universal computing system, we design the minimal logical gates NOT, AND and NOT-AND. © 1997 John Wiley & Sons, Ltd. |
