. Action systems is a formalism designed for the construction of parallel and distributed systems in a stepwise manner within the refinement calculus. In this paper we show how action systems can be derived and refined within a mechanical proof tool, the B-Tool. We describe how action systems are embedded in B-Tool. Due to this embedding we can now develop parallel and distributed systems within the B-Tool. We also show how a typical and nontrivial refinement rule, the superposition refinement rule, is formalized and applied on action systems within B-Tool. A derivation towards a distributed load balancing algorithm is given as a case study. 1 Introduction Action systems are used to construct parallel and distributed systems in a stepwise manner as described by Back et al. [2, 4]. They are often developed using a poweful program modularization and structuring method called superposition [7, 9, 2]. In superposition some new functionality is added to an algorithm in the form of additio...

Action systems is a formalism designed for the construction of parallel and distributed systems in a stepwise manner within the refinement calculus. In this paper we show how action systems can be derived and refined within a mechanical tool, the B-Toolkit. We describe how action systems are embedded in the B-Method, the method supported by the B-Toolkit. Furthermore, we show how a typical and nontrivial refinement rule, the superposition refinement rule, is formalized and applied on action systems within the B-Method. In addition to providing tool support for action systems refinement we also extend the application area of B-Method to cover parallel and distributed systems. A derivation towards a distributed load balancing algorithm is given as a case study. Keywords: tools and techniques, action systems, superposition refinement, distributed systems TUCS Research Group Programming Methodology Research Group 1 Introduction Action systems are used to construct parallel and distribu...