Systems formulation of a theory of diagnosis from first principles

The author reformulates the theory of diagnosis given by R. Reiter (see Artificial Intelligence vol.32, no.1, p.57-95, 1987) in a systems theory framework and extends it to explicitly cover admissible fault models. The reformulation allows one to use straightforward set theoretic and algebraic concepts to characterize the main theorem relating diagnoses and conflict sets. The authors distinguish between weak and strong diagnoses and show that nonminimal strong diagnoses (multiple faults) may arise where the class of admissible fault models of components is restricted. They argue that the effectiveness of troubleshooting may be greatly enhanced by taking such diagnoses into account. This is true since the nature of the admissible fault model classes can dramatically affect the diagnoses generated. In particular, diagnoses that are not based on models of potential fault behaviors may be quite deceptive in relation to actual failed system behavior. The full family of strong diagnoses, although potentially much more computationally demanding than the minimal diagnoses, should be taken as the basis for troubleshooting