Abstract: The present paper covers new collision results and evol ution stability for the sub-classes of Wolfram Class Ⅳ in one-dimensional cellular automata with k=2, r=2. By planting the gene-pieces of the two su b-classes into the original environment and making them collision, we obtained three objects by the differential distance of gene-pieces. We also introduced the conception of the evolution stability of Wolfram Class Ⅳ, and found that the sub-classes of Wolfram Class Ⅳ are unstable.

Key words: cellular automaton, Wolfram Class Ⅳ, evolution stability