In a framework allowing infinitely many individuals, I prove that coalitionally strategyproof social choice functions satisfy tops only. That is, they depend only on which alternative each indvidual prefers the most, not on which alternative she prefers the second most, the third, \dots, or the...

Consider the problem of allocating k identical, indivisible objects among n agents, where k is less than n. The planner's objective is to give the objects to the top k valuation agents at zero costs to the planner and the agents. Each agent knows the identity of those k agents, as well as her...

Acyclicity of individual preferences is a minimal assumption in social choice theory. We replace that assumption by the direct assumption that preferences have maximal elements on a fixed agenda. We show that the core of a simple game is nonempty for all profiles of such preferences if and only...

The planner wants to give k identical, indivisible objects to the top k valuation agents at zero costs. Each agent knows her own valuation of the object and whether it is among the top k. Modify the (k 1)st-price sealed-bid auction by introducing a small participation fee and the option not to...