Prolog-based Attached Procedures in the Frame-based Knowledge Representation System ZERO

Abstract

This paper presents the design concept and implementation of mechanisms of the Prolog-based attached procedure for the ZERO knowledge representation system. ZERO is an extension of FMS (Frame Manipulation System), a general purpose frame-based system, ZERO and which is embedding Prolog. The ZERO system can handle a set of Prolog statements which works like Lisp-oriented attached procedure. The set of Prolog statements is called attached clauses, which is activated by a message from another frame just like as in Lisp-oriented procedural knowledge. Since the knowledge description in clauses has higher modularity, it is easy to combine those clauses which are defined at several class frames in a hierarchy to a set of attached clauses by means of an inheritance control. The inheritance on attached clauses has two different characteristics; inheritances of facts and of procedures. By combining Prolog statements and Lisp-based procedures, highly flexible knowledge based systems could be achieved in sense that users can select the suitable language for specifying the procedural knowledge according to a type of a problem. In order to represent the behavior of conceptual objects in frames, the mechanisms both for message passings and inheritance control with attached clauses are useful by describing in clauses. We have evaluated usefulness of these mechanisms representing RHEUM model. It should be stressed that ZERO is designed to achieve powerful and flexible knowledge representation system by combining strong features of a frame model and Prolog, by embedding the Prolog system within the frame system. We believe that the understandability of representing procedural knowledge and the utilization of it has been significantly improved by this way.