We establish that the fraction of preference profiles for which the random serial dictatorship allocation is ordinally efficient vanishes for allocation problems with many object types. We consider also a probabilistic setting where in expectation agents have moderately similar preferences...

This paper examines a model of duopoly firms selling to an exogenously formed buyer group consisting of members with heterogeneous preferences. Two research questions are addressed: (1) when is it optimal for a buyer group to commit to exclusive purchase from a single seller, and (2) how does...

A mechanism implements a social choice correspondence f in mixed Nash equilibrium if at any preference profile, the set of all pure and mixed Nash equilibriumoutcomes coincides with the set of f-optimal alternatives at that preference profile. This definition generalizes Maskin’s definition of...

A mechanism implements a social choice correspondence f in mixed Nash equilibrium if at any preference profile, the set of all pure and mixed Nash equilibrium outcomes coincides with the set of f-optimal alternatives at that preference profile. This definition generalizes Maskin's definition of...

The Arrow index of a fuzzy choice function C is a measure of the degree to which C satisfies the Fuzzy Arrow Axiom, a fuzzy version of the classical Arrow Axiom. The main result of this paper shows that A(C) characterizes the degree to which C is full rational. We also obtain a method for...

This note studies the problem of implementing social choice correspondences in environments where individuals have doubts about the rationality of their opponents. We postulate the concept of "-minimax regret as our solution concept and show that social choice correspondences that are Maskin...