The model-based approach to diagnosis started to be investigated by A.I. researchers in the late seventies, as a possible alternative to the expert-system approach [9]. At that time diagnosis was one of the largest categories of expert systems in use; nonetheless the use of expert knowledge in diagnosis started to show some major limitation [18], especially when applied to diagnosis of artifact...

DEXSY2 is a dental expert system, which diagnoses oral diseases and offers a treatment course. The system which is designed and implemented from scratch is capable of diagnosing among thirty five oral diseases and offering a course of treatment for each. It uses a decision tree for its representation of knowledge, and each of its nodes contains a frame. The knowledge base of the system contains...