On Bisimulations for the Asynchronous - calculus ?

The asynchronous-calculus is a variant of the-calculus where message emission is non-blocking. Honda and Tokoro have studied a semantics for this calculus based on bisimulation. Their bisimulation relies on a modiied transition system where, at any moment, a process can perform any input action. In this paper we propose a new notion of bisimulation for the asynchronous-calculus, deened on top of the standard labelled transition system. We give several characterizations of this equivalence including one in terms of Honda and Tokoro's bisimulation, and one in terms of barbed equivalence. We show that this bisimulation is preserved by name substitutions, hence by input preex. Finally, we give a complete axiomatization of the (strong) bisimulation for nite terms.