Diagnostic reasoning either automated or conducted by diagnosticians relies on having a set of symptoms and trying to match them against a (sparse) matrix containing the complete set of diseases and their corresponding symptioms. Whenever a symptom manifests itself, the diagnostician activates in this matrix several possible diseases which could manifest that symptom. The reasoning proceeds up to the point in which a very small subset of diseases (ideally one) are known to cause those symptoms.Efita 2009
