  Valuation-based system (VBS) provides a general framework for representing
knowledge and drawing inferences under uncertainty. Recent studies have shown
that the semantics of VBS can represent and solve Bayesian decision problems
(Shenoy, 1991a). The purpose of this paper is to propose a decision calculus
for Dempster-Shafer (D-S) theory in the framework of VBS. The proposed calculus
uses a weighting factor whose role is similar to the probabilistic
interpretation of an assumption that disambiguates decision problems
represented with belief functions (Strat 1990). It will be shown that with the
presented calculus, if the decision problems are represented in the valuation
network properly, we can solve the problems by using fusion algorithm (Shenoy
1991a). It will also be shown the presented decision calculus can be reduced to
the calculus for Bayesian probability theory when probabilities, instead of
belief functions, are given.
