Strategies in Modular System Design by Interface Rewriting

The design of a modular system using a predefined set of modules with a given import or export interface, has been reduced to the problem of generating a specification in an algebraic specification grammar. In this paper we provide not only syntactical criteria (independent of the target specification) for avoiding unnecessary searches, but also a strategy to adopt in choosing the rewrite rules. The former development has been influenced by similar work on graph grammars, whereas we introduce the concepts of similarity between specifications and a definition of value in order to guide the search algorithm for the latter. A further development of the similarity concept allows to consider a set of specification as a metric space, giving a precise definition of distance function.