(7) Fast Hypothetical Reasoning System

Although the framework of hypothetical reasoning is very useful, it has not been widely used due mainly to its low efficiency. This study aims to develop software tools that allow our achievements on an efficient hypothetical reasoning method to be used in wider applications, thus expanding the use of the new knowledge processing framework. In particular, we focus on a framework of weighted (or cost-based) hypothetical reasoning, which assigns numerical weights to possible element hypotheses and obtains an optimal solution hypothesis with minimal sum of the weights (or const). Our method called the networked bubble propagation (NBP) method for this problem can compute a near-optimal solution in polynomial time. Software implementation based on this method includes two versions, i.e., a propositional-logic version and a predicate-logic version which handles range-restricted predicate Horn clauses. The propositional-logic version called "nbp1" has been completed as a software tool in 1995. A predicate-logic version employing this "nbp1" as its sub-mechanism is implemented, but still needs some improvements as of Feb. 1997.