Knowledge verification in expert systems combining declarative and procedural representations

Abstract

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 rules. The algorithm has three stages. The first stage of the algorithm converts the procedures into rules which are added to the existing rules to produce the equivalent rule set. The second stage of the algorithm partitions the equivalent rule set into decision subtables by regrouping rules with similar conditions in their if part or similar actions in their then part. In the third stage, each subtable is checked for consistency by looking for redundant rules and potentially or strictly conflicting rules. Completeness is verified by looking for unreferenced attribute values and missing rules. The algorithm is designed to automatically check any modification to the knowledge base as the system is being developed or updated. We demonstrate the algorithm on examples from process control.