CCS semantics via proved transition systems and rewriting logic

We consider a slight variant of the CCS calculus and we analyze two operational semantics defined in the literature: the first exploits Proved Transition Systems (PTSs) and the second Rewriting Logic (RL). We show that the interleaving interpretation of both semantics agree in that they dene the same transitions and exhibit the same nondeterministic structure. In addition we study causality in CCS computations. We recall the treatment via PTSs that exhibits the notion of causality presented in the literature and we show how to recast it in the RL semantics via suitable axioms.