Abstract
In this article, the relational structures of the numerical probability, belief, plausibility, and ambiguity functions are analyzed. A non-numerical measure is introduced for each numerical function. These non-numerical measures can be viewed as qualitative measures of ignorance, as they define the same relational structures as their numerical counterparts. The result of this analysis is important because it establishes the basis for adopting a particular non-numerical function to measure ignorance. © 1996 John Wiley & Sons, Inc.
