Abstract:The drawbacks pure probabilistic methods and the certainty factor model have led us in recent years to consider alternate approaches. Particularly appealing is the mathematical theory evidence develop...The drawbacks pure probabilistic methods and the certainty factor model have led us in recent years to consider alternate approaches. Particularly appealing is the mathematical theory evidence developed by Arthur Dempster. We are convinced it merits careful study and interpretation in the context expert systems. This theory was first set forth by Dempster in the 1960s and subsequently extended by Glenn Sharer. In 1976, the year after the first description CF’s appeared, Shafer published A Mathematical Theory Evidence (Shafer, 1976). Its relevance to the issues addressed in the CF model was not immediately recognized, but recently researchers have begun to investigate applications the theory to expert systems (Barnett, 1981; Friedman, 1981; Garvey et al., 1981). We believe that the advantage the Dempster-Shafer theory over previous approaches is its ability to model the narrowing the hypothesis set with the accumulation evidence, a process that characterizes diagnostic reasoning in medicine and expert reasoning in general. An expert uses evidence that, instead bearing on a single hypothesis in the original hypothesis set, often bears on a larger subset this set. The functions and combining rule the Dempster-Shafer theory are well suited to represent this type evidence and its aggregation. For example, in the search for the identity an infecting organism, a smear showing gram-negative organisms narrows the hypothesis set all possible organisms to a proper subset. This subset can also be thought as a new hypothesis: the organism is one the gram-negative organisms. However, this piece evidence gives no information concerning the relative likelihoods the organisms in the subset. Bayesians might assume equal priors and distribute the weight this evidence equally among the gram-negative organisms, but, as Shafer points out, they would thus fail to distinguish between uncertainty, or lack of knowledge, andRead More
Publication Year: 1990
Publication Date: 1990-06-01
Language: en
Type: book
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Cited By Count: 171
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