Dybvig ( 1988a , 1988b ) solves in a complete market setting the problem of finding a payoff that is cheapest possible in reaching a given target distribution (“cost-efficient payoff”). In the presence of ambiguity, the distribution of a payoff is, however, no longer known with certainty. We...

We suggest a concept of convexity of preferences that does not rely on any algebraic structure. A decision maker has in mind a set of orderings interpreted as evaluation criteria. A preference relation is defined to be convex when it satisfies the following: if for each criterion there is an...

We suggest a concept of convexity of preferences that does not rely on any algebraic structure. A decision maker has in mind a set of orderings interpreted as evaluation criteria. A preference relation is defined to be convex when it satisfies the following: if for each criterion there is an...

The paper generalizes Kuhn's Theorem to extensive form games in which players condition their play on the realization of ambiguous randomization devices and use a maxmin decision rule to evaluate the consequences of their decisions. It proves that ambiguous behavioral and ambiguous mixed...

The paper generalizes Kuhn's Theorem to extensive form games in which players condition their play on the realization of ambiguous randomization devices and use a maxmin decision rule to evaluate the consequences of their decisions. It proves that ambiguous behavioral and ambiguous mixed...

Raiffa (1961) criticizes ambiguity-averse preferences by claiming that hedging is possible with randomization of choices. We argue that the timing of randomization is crucial for hedging. Ex-ante randomizations, which are randomizations before a state is realized, could provide only ex-ante...

In Anscombe and Aumann's (1963) domain, there are two types of mixtures. One is an ex-ante mixture, or a lottery on acts. The other is an ex-post mixture, or a state-wise mixture of acts. These two mixtures have been assumed to be indifferent under the Reversal of Order axiom. However, we argue...

In Anscombe and Aumann’s (1963) domain, there are two types of mixtures. One is an ex–ante mixture, or a lottery on acts. The other is an ex–post mixture, or a state–wise mixture of acts. These two mixtures have been assumed to be indifferent under the Reversal of Order axiom. However,...