Prolog/Rex inference engine

Abstract: Prolog/Rex supports the construction of knowledge‐based systems, allowing frames (Prolog/Rex concepts) and rules to be combined, and providing language level support for hypothetical reasoning and assumption‐based truth maintenance (Prolog/Rex viewpoint mechanism). To increase run‐time performance during rule execution, Prolog/Rex provides two complementary rule compilation techniques: the simple indexing scheme and the heavily modified Rete expansion method. To improve the efficiency of the inference engine, we built an agenda‐based rule manager that uses priority mechanism and/or heuristics embedded in meta‐rules to control the rule firing order. Forward‐ and backward‐chaining can be combined within the same program.