Belief functions can be taken as an alternative to the classical probability theory, as a generalization of this theory, but also as a non-traditional and sophisticated application of the probability theory. In this paper we abandon the idea of numerically quantified degrees of belief in favour of the case when belief functions take their vahies in partially ordered sets, perhaps enriched to lower or upper semilattices. Such structures seern to be the most general ones to which reasonable and nontrivial parts of the theory of belief functions can be extended and generalized.
Belief functions can be taken as an alternative to the classical probability theory, as a generalization of this theory, but also as a non-traditional and sophisticated application of the probability theory. In this paper we abandon the idea of nnmerically quantified degrees of belief in favour of the case when belief functions take their values in partially ordered sets, perhaps enriched to lower or upper semilattices. Such structures seern to be the most general ones to which reasoriable and nontrivial parts of the theory of belief functions can be extended and generalized.