Logic programming in APL

The programming of an expert system requires a language for specifying the rules that an expert uses, a data base for storing his knowledge, and a suitable interactive system. Logic programming has been described as a way of implementing expert systems. With logic programming, rules are expressed as assertions of what is true when certain conditions are true. To be true, the assertion has to be based upon fact or upon an inference derived from facts. This paper describes an implementation of a PROLOG-like language in APL. The intent is to achieve logic programming capability while retaining the full facility of APL. PROLOG is both an extension of LISP, thereby satisfying the needs of the Artificial Intelligence community, and a language for relational databases. This implementation leans toward the relational data base approach.