Managing flow of control in diagnostic expert systems

It is argued that many expert systems for equipment fault diagnosis have lost sight of the goal of modeling the actual procedures of the domain expert. It is shown that it is possible to model such expertise in the design of flow of control in such expert systems, i.e. in the architecture as well as the rule base. The authors present as examples two such features from an expert system for the maintenance of mail processing equipment: a focus mechanism which guides the interaction through a hierarchical partition of the rule base, and a specialized procedure mechanism for capturing knowledge about connected sequences of diagnostic activity