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.