1 Department of Information Technology, Technical University of Denmark2 Åbo Academy University
An action system framework is a predicate transformer based method for modelling and analysing distributed and reactive systems. The actions in action systems are statements in Dijkstra's guarded command language, and their semantics is given by predicate transformers. Recently, we introduced a differential action, which allows differential equations as primitive actions. The extension allows us to model hybrid systems with both continuous and discrete behaviour. The main result of this paper is an extension of such a hybrid action system with parallel composition. The extension does not change the original meaning of the parallel composition, and therefore also the ordinary action systems can be composed in parallel with the hybrid action systems.