Clifford Grossner, Alun D. Preece, P. Gokul Chander, T. Radhakrishnan, Ching Y. Suen
In order to measure and analyze the performance of rule-based expert systems, it is necessary to explicate the internal structure of their rule bases. Although a number of attempts have been made in the literature to formalize the structure of a rule base using the notion of a rule base execution path, none of these are entirely adequate. This paper reports a new formal definition for the notion of a rule base execution path, which adequately supports both validation and performance analysis of rule-based expert systems. This definition for the execution paths in a rule base has been embodied in a rule base analysis tool called Path Hunter. Path Hunter is used to analyse a rule base consisting of 442 CLIPS rules. In this analysis, the problem of combinatorial explosion, which arises during path enumeration, is controlled due to the manner in which paths are defined. The analysis raises several issues which should be taken into account in the engineering of rule-based systems.