Modular Multiset Rewriting.

Rule-based languages are being used for ever more ambitious applications. As program size grows however, so does the overhead of team-based development, reusing components, and just keeping a large flat collection of rules from interfering. In this paper, we propose a module system for a small logically-motivated rule-based language. The resulting modules are nothing more than rewrite rules of a specific form, which are themselves just logic formulas. Yet, they provide some of the same features found in advanced module systems such as that of Standard ML, in particular name space separation, support for abstract data types, and parametrization functors in ML. Our modules also offer essential features for concurrent programming such as facilities for sharing private names. This approach is directly applicable to other rule-based languages, including most forward-chaining logic programming languages and many process algebras.