Casl — the Common Algebraic Specification Language

Abstract

Casl is an expressive specification language that has been designed to supersede many existing algebraic specification languages and provide a standard. Casl consists of several layers, including basic (unstructured) specifications, structured specifications and architectural specifications; the latter are used to prescribe the modular structure of implementations. We describe a simplified version of the Casl syntax, semantics and proof calculus for each of these three layers and state the corresponding soundness and completeness theorems. The layers are orthogonal in the sense that the semantics of a given layer uses that of the previous layer as a “black box�?, and similarly for the proof calculi. In particular, this means that Casl can easily be adapted to other logical systems. We conclude with a detailed example specification of a warehouse, which serves to illustrate the application of both Casl and the proof calculi for the various layers.