On Performance Congruences for Process Algebras

AbstractBased on the hypothesis of durational actions and process synchronization with “busy waiting” mechanism,performance equivalencehas been proposed to introduce a simple form of performance evaluation in process algebras. This equivalence enjoys many of the pleasant properties of those in the untimed setting but it is not a congruence for parallel composition with synchronization. In this paper we give a bisimulation-based characterization of the coarsest congruence contained within performance equivalence (and discuss alternative formulations). This problem was left open in several papers. We study how the new equivalence, calledperformance congruence, relates with other closed equivalences in the literature and show that, unlike other proposals, it is a natural extension of those standard in the untimed setting. The weak version of performance congruence, which abstracts from internal details, is also studied. A number of examples of processes related or taken apart by performance congruence, and its weak version, are provided. A nontrivial one is also presented to illustrate the utility of the new congruences. The paper concludes with further observations concerning performance congruence and with a discussion on related and further interesting work