**Maxmin Expected Utility
over Savage Acts with a Set of Priors**

**Abstract**:
This paper provides an axiomatic foundation for a maxmin expected utility over
a set of priors (MMEU) decision rule in an environment where the elements of
choice are Savage acts. This characterization complements the original axiomatizations
of MMEU developed in a lottery-acts (or Anscombe-Aumann) framework by Gilboa
and Schmeidler (1989). MMEU preferences are of interest primarily because they
provide a natural and tractable way of modeling decision makers who display
an aversion to uncertainty or ambiguity. The novel axioms are formulated using
standard sequence techniques, which allow cardinal properties of utility be
expressed directly through preferences.