Explaining by evidence

Abstract

Given a system description an d its observed behaviour, there usually exist several possible explanations of the situation. DiOE erent explanations may contradict one an other and suggest con¯icting actions. So, in order to take proper actions sanctioned by the real situation, we need to single out an explanation that is most adequate to the reality. Existing methods for determining of such a best explanation require an extensive statistical knowledge about the system behaviour, which often is either only partially availa ble or not satisfactorily reliable. Trying to overcome this lack of data, we introduce the notion of evidence as a measure of credibility of beliefs based on the seman tic information contained in the system and supplied by the observations. Reasoning by evidence is ap plied to the process of determining a best abductive explanation. Th e notion of conjecture is presented as a generalization of explanation. Then reasoning by evidence is applied to testing and re® ning of diagnoses.