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Measuring ambiguity in the evidence theory
Jousselme, A.-L.; Chunsheng Liu; Grenier, D.; Bosse, E.;
Systems, Man and Cybernetics, Part A, IEEE Transactions on
Volume 36,
Issue 5,
Sept. 2006
Page(s):890
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903
Abstract:
In the framework of evidence theory, ambiguity is a general term proposed by Klir and Yuan in 1995 to gather the two types of uncertainty coexisting in this theory: discord and nonspecificity. Respecting the five requirements of total measures of uncertainty in the evidence theory, different ways have been proposed to quantify the total uncertainty, i.e., the ambiguity of a belief function. Among them is a measure of aggregate uncertainty, called AU, that captures in an aggregate fashion both types of uncertainty. But some shortcomings of AU have been identified, which are that: 1) it is complicated to compute; 2) it is highly insensitive to changes in evidence; and 3) it hides the distinction between the two types of uncertainty that coexist in every theory of imprecise probabilities. To overcome the shortcomings, Klir and Smith defined the TU/sub 1/ measure that is a linear combination of the AU measure and the nonspecificity measure N. But the TU/sub 1/ measure cannot solve the problem of computing complexity, and brings a new problem with the choice of the linear parameter /spl delta/. In this paper, an alternative measure to AU for quantifying ambiguity of belief functions is proposed. This measure, called Ambiguity Measure (AM), besides satisfying all the requirements for general measures also overcomes some of the shortcomings of the AU measure. Indeed, AM overcomes the limitations of AU by: 1) minimizing complexity for minimum number of focal points; 2) allowing for sensitivity changes in evidence; and 3) better distinguishing discord and nonspecificity. Moreover, AM is a special case of TU/sub 1/ that does not need the parameter /spl delta/.
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