A synchronous pi-calculus

The SL synchronous programming model is a relaxation of the Esterel synchronous model where the reaction to the absence of a signal within an instant can only happen at the next instant. In previous work, we have revisited the SL synchronous programming model. In particular, we have discussed an alternative design of the model including thread spawning and recursive definitions, introduced a CPS translation to a tail recursive form, and proposed a notion of bisimulation equivalence. In the present work, we extend the tail recursive model with first-order data types obtaining a non-deterministic synchronous model whose complexity is comparable to the one of the pi-calculus. We show that our approach to bisimulation equivalence can cope with this extension and in particular that labelled bisimulation can be characterised as a contextual bisimulation

Trace and Testing Equivalence on Asynchronous Processes

We study trace and may-testing equivalences in the asynchronous versions of CCS and π-calculus. We start from the operational definition of the may-testing preorder and provide finitary and fully abstract trace-based characterizations for it, along with a complete in-equational proof system. We also touch upon two variants of this theory by first considering a more demanding equivalence notion (must-testing) and then a richer version of asynchronous CCS. The results throw light on the difference between synchronous and asynchronous communication and on the weaker testing power of asynchronous observations