Maxmin expected utility over savage acts with a set of priors

This paper provides an axiomatic foundation For a maxmin expected utility o ver a set of priors (MMEU) decision rule in an environment where the elemen ts of choice are Savage acts. This characterization complements the origina l axiomatization of MMEU developed in a lottery-acts (or Anscombe-Aumann) f ramework by I. Gilboa and D. Schmeidler (1989 J, Math. Econ. 18, 141-153). MMEU preferences are of interest primarily because they provide a natural a nd tractable way of modeling decision makers who display an aversion to unc ertainty or ambiguity. The novel axioms are formulated using standard seque nce techniques, which allow cardinal properties of utility to be expressed directly through preferences. Journal of Economic Literature Classification Number: D81. (C) 2000 Academic Press.