EFFICIENT HYPOTHETICAL REASONING SYSTEM FOR PREDICATE-LOGIC KNOWLEDGE-BASE

A hypothetical reasoning system is an important framework in the devel opment of advanced knowledge-based systems. It can be effectively appl ied to many practical problems including model-based diagnosis, and de signs. However, the inference speed of its PROLOG-based implementation is slow, and this is particularly because of inefficient backtracking . In order to overcome this problem, a fast hypothetical reasoning mec hanism for propositional-logic knowledge has been developed by combini ng the advantages of forward and backward reasoning styles. This fast mechanism, however, cannot be applied to hypothetical reasoning with p redicate-logic knowledge where variables are included as arguments. Th e paper presents a fast hypothetical reasoning mechanism for predicate -logic knowledge as an extension of the above idea. A reasoning method developed in the deductive database area is effectively utilized to r ealize this fast mechanism, which can even manipulate recursive rules.