Modifiable Combining Functions

Glenn Shafer Prakash P. Shenoy School of Business University of Kansas Lawrence, Kansas 66045 Modifiable combining functions are a synthesis of two general approaches to combining evidence. Be­ cause they facilitate the acquisition, representation, explanation, and modification of expert knowl­ edge about combinations of evidence, they are presented as a device for knowledge engineers, not as a normative theory of evidence combination. The basic idea of modifiable combining functions is to acquire degrees of belief for a subset of all possible combinations of evidence, then infer degrees of belief for other combinations in the set. If, in the course of knowledge engineering, a -particular degree of belief is challenged, then it (and others) can be modified by an appropriate method.