Non-uniform cellular automata: Evolution in rule space and formation of complex structures

Cellular automata are dynamical systems in which space and time are discrete, where each cell obeys the same rule and has a nite number of states. In this paper we study non-uniform cellular automata, i.e. with non-uniform local interaction rules. Two different models are described. In the first a cell's rule may be regarded as a genotype whose phenotypic effect is achieved by rule application. Our focus is on evolution in rule space starting from a random gene pool, i.e. rule population. The second model focuses on the study of complex structures formed by a small number of rules, where the term `complex' denotes a structure consisting of simple grid cells, acting as a single \organism".