Higher-Level Synchronising Devices in Meije-SCCS

Abstract In an algebraic setting for parallelism and synchronisation due to R. Milner, we define a wide variety of synchronising operators on processes. We introduce them by the semantical conditional rules they obey. We prove they are higher-level nonprimitive operators from the original SCCS calculus, showing how to meet their behaviours with primitive expressions. Our purposes are: study of expressiveness—either ‘semantic’, in the realm of transition systems, or ‘syntaxic’, through translation of other formalisms in the calculus. Such operators allow one to specify formally sophisticated synchronisation modes dealing with (operational) products and transformations of transition systems, and still not lose their informal appealing intuition; for we then forget the realisation working with Meije -SCCS elementary synchronisation mechanisms (the mechanics below the hood). The defining rules are syntactically given, except for the allowed relations on the components' actions monoids. This ‘semantical’ aspect allows us to treat many ‘calculability’ issues. This is especially true of closed terms, where we may claim constructive ‘universality’ amongst transition systems. The case of operators seems slightly more intricate. The proof of our main result has led us to a technical shaping of equivalence proofs for open expressions which shows to be interesting in its own right.