KNOWLEDGE VERIFICATION IN EXPERT-SYSTEMS COMBINING DECLARATIVE AND PROCEDURAL REPRESENTATIONS

We present an algorithm to verify the consistency and completeness of an object-oriented structured knowledge base of an expert system which combines procedures with a declarative representation using if then r ules. The algorithm has three stages. The first stage of the algorithm converts the procedures into rules which are added to the existing ru les to produce the equivalent rule set. The second stage of the algori thm partitions the equivalent rule set into decision subtables by regr ouping rules with similar conditions in their if part or similar actio ns in their then part. In the third stage, each subtable is checked fo r consistency by looking for redundant rules and potentially or strict ly conflicting rules. Completeness is verified by looking for unrefere nced attribute values and missing rules. The algorithm is designed to automatically check any modification to the knowledge base as the syst em is being developed or updated. We demonstrate the algorithm on exam ples from process control.