Transition rule

A transition rule is a combination of a condition and a transition: simply an ordered pair (c; t) where c is a condition and t is a transition. It is possible to define a cellular automaton by writing down a set of transition rules, such that for every condition that can possibly occur, the set of transition rules contains exactly one rule that "matches" that condition. In other words, the transition rules must cover all possible scenarios and leave no ambiguity or contradictions.