A Knowledge Representation Scheme Using Ordinary Words and the Inference Mechanism on Order-sorted Logic

Abstract

We propose a knowledge representation scheme (called WPL) and an inference method for the scheme. In WPL, both simple sentence and complex sentence are represented in one atomic formula. Subordinate clauses in a complex sentence are embedded into the formula forming the main clause. WPL is an extended order-sorted logic that can deal with structured sort symbols consisting of multiple ordinary words like noun phrases. Each word in a sort symbol can represent a general concept or a particular object. If it is the latter, each word stands for a variable or constant having itself as a sort symbol. It may also be a proper noun or variable itself. The inference processes for WPL is executed based on the resolution principle, semantically interpreting the sort symbols word by word. We extend the inference rules proposed by Beierle et al. in order to deal with complex sort symbols. This paper also describes an application scheme of the proposed inference rules and an algorithm for judging the subsort relation between complex sort symbols.