LOTOS-like process algebras with urgent or timed interactions

Abstract

A LOTOS-like timed process algebra is first introduced, which offers operators for specifying the urgency of a specified action, but also of an interaction involving two or more processes, and other fundamental time-related behaviours. The formal semantics of the language consists of two independent sets of inference rules which handle, respectively, the occurrence of actions and the passing of time. The language can specify in a natural way the “wait-until-timeout” scenario, and, due to its time related operators, it can simulate Turing machines. A refinement is then presented where one can specify time intervals for the occurrence of actions and interactions. The models appear as a most natural transposition in the realm of process algebras of the well known Time Petri Nets of Merlin and Farber and, as such, are proposed as a simple, sound and effective basis for timed extensions of the LOTOS standard.