Rule effectiveness in rule-based systems: A credit scoring case study

Rule-based systems may sometimes grow very large, making their acceptance by users and their maintenance quite problematic. One therefore needs to make rule-bases as compact as possible. The classical definition of rule redundancy in the literature is based upon logic and graph theory. Another, complementary, view of redundancy is proposed here. The suggested approach is based on the contribution of individual rules to the overall system's accuracy. It is shown here, though an analysis of a real-world credit scoring rule-based system, that by taking into account system's accuracy, one can sometimes significantly reduce the size of a rule-base; even one which is already free from logic-related abnormalities. The approach taken here is not proposed as a substitution to classical logic and graph-based methods. Rather, it complements them. (c) 2007 Elsevier Ltd. All rights reserved.