Refinement of Structured Interactive Systems.

The refinement concept provides a formal tool for addressing the complexity of software-intensive systems, by verified stepwise development from an abstract specification towards an implementation. In this paper we propose a novel notion of refinement for a structured formalism dedicated to interactive systems, that combines a data-flow with a control-oriented approach. Our notion is based on scenarios, extending to two dimensions the trace-based definition for the refinement of classical sequential systems. We illustrate our refinement notion with a simple example and outline several extensions to include more sophisticated distributed techniques.