Liveness and Safety in Concurrent Constraint Programs

In this section we recall the standard de nitions of temporal operators in the notation of Clarke s CTL The operators are used to specify liveness properties something good will nally happen and safety properties nothing bad will happen In non deterministic systems one has to make precise whether the speci cation refers to some or to all execution sequences starting from a given state Let S T be a transition system i e a set S of states together with a non deterministic transition function T S P S i e a mapping from S to the powerset of S Given a property of states i e a set Prop S we can de ne a new set of states satisfying a CTL style temporal property in one of the following ways