Design schemes for rule-based systems

The design of rule-based systems is often plagued by errors and anomalies. In this paper, we assume that a way to abstract the domain knowledge is to use goals. The problem solving model of the system is in terms of goal inferences that occur in the rule base level using sets of rule sequences called paths. The mapping between goals and their representation in a rule base is one-to-many and results in several design schemes for rule-based systems: the various design schemes impose different mapping restrictions for representing a goal in a rule base. Thus, the applicability of a design scheme and the relationships between the various design schemes are important factors that need to be considered before choosing a scheme for development. We explore one specific relationship, called inheritance, between the design schemes. The pros and cons of using two schemes D-A and D-B, that have an inheritance relationship between them are analyzed for development versus maintenance. The paper also provides metric measures to facilitate general comparison between design schemes. Finally, we outline an application of inheritance for automatically transforming a rule base from one scheme into another.