Global Timed Bisimulation: An Introduction

Bisimulations are a broadly used formalism to deene the semantics of process algebras. In particular, by means of weak bisimulation most of the internal activity of processes may be abstracted. Unfortunately, this is not fully accomplished: for instance, the internal choice operator becomes non-associative since bisimulation can see the branching structure of processes. In this paper we propose global timed bisimulation as a weakening of weak timed bisimulation. Global timed bisimulation is deened exactly as weak timed bisimulation once ordinary transitions are replaced by the adequate notions of generalized transitions. In order to asses the deenition of our global timed bisimulation we present a collection of small examples that illustrate each of the clauses of that deenition. Finally, a more elaborated example is presented to summarize the main properties of that notion. 1. INTRODUCTION Operational semantics is probably the simplest and more intuitive way to give semantics to any process language. It is usually deened by means of a labeled transition system which contains the transitions, P l ?! P 0 that each process can execute. But these semantics are not abstract enough since they contain the full information about the syntax of processes. Bisimulations 9] are the usual way to solve this problem, by deening a slightly weaker equivalence which is a rather reasonable, simple and nice way to deene the semantics of non-deterministic processes.