A type driven hardware engine for Prolog clause retrieval over a large knowledge base

Abstract

Whereas existing Prolog systems are very effective at handling small knowledge bases, they are not very efficient at and often incapable of handling large sets of clauses. Large knowledge bases which may comprise millions of clauses and are shared by a number of users, may need to reside in secondary memory. In such cases exhaustive search is inordinately slow. Various approaches have been put forward for handling the problem, most of which involve coupled systems (loosely or tightly coupled). A Prolog data/knowledge based system which provides an integrated solution to the problem is being developed. An essential element in this system is the CLAuse Retrieval Engine, CLARE, which is a special purpose hardware engine designed to perform selective retrieval of data from disk in order to identify all potential clauses which will be required for full unification during a query. The engine consists of two separate hardware components, which together form a two-stage filtering configuration. This paper concentrates on the second stage filter which is concerned with partial test unification.