1989 Volume 2 Issue 2 Pages 54-61
In this paper, the set-cover theoretical diagnosis model proposed by Reggia et al. is extended to allow a fuzzy occurrence of symptoms. In the Reggia's model, each disorder has the set of possible manifestations which is represented by the possible causal relations, and this relation represents the knowledge that disorder ci may cause manifestation ej. In addition to this relation, we introduce the necessary causal relation which represents the knowledge that disorder ci always causes manifestation ej. By this relation, the information that manifestation ej doesn't occur in the patient can be available for the diagnosis process. In order to diagnose the fuzzy symptoms, we propose the method for constructing the belief function on the frame of diagnosis hypotheses. The upper and lower probabilities of each diagnosis hypothesis and each disorder are obtained from this belief function.
