Using polymorphism to improve expert system maintainability

The problems encountered in applying object-oriented programming to expert systems are described. A production system called Clasp, which addresses these difficulties, is presented. Clasp integrates methods, production rules, and terminological definitions for classes. The approach is a further generalization of Common Loops and the Common Lisp Operating System, which have all extended notion of methods in which all argument types can describe the applicability of methods. The system was designed to improve the modularity and reusability of the rule base, to support the development of a more consistent and homogeneous knowledge base, and to enhance the predictability of rules. >