 Dempster-Shafer theory is more general than the theory of subjective probability in the sense that the latter requires additivity, whereas the former requires only super-additivity. However, most authors agree that DS theory is not as general as imprecise probability theory. The reason is that DS belief functions can be represented as convex sets of probabilities. More precisely, for every DS belief function \(\Bel\) there is a convex set of probabilities \(\mathcal{P}\) such that \(\Bel(A)=\min \{ p(A) : p \in \mathcal{P}\}\) and \(P(A) = \max \{ p(A) : p\in\mathcal{P}\} \) (Walley 1991). As not every convex set of probabilities can be represented as a DS belief function, sets of probabilities arguably provide the most general framework we have come across so far.