Which decision rule should we use to make a binary collective choice? While voting procedures are applied ubiquitously, they are criticized for being inefficient. Using monetary transfers, efficient choices can be made at the cost of a budget imbalance. Is it optimal to do so? And why are...

An anonymous social choice function for a large atomless population maps cross-section distributions of preferences into outcomes. Because any one individual is too insignificant to affect these distributions, every anonymous social choice function is individually strategy- proof. However, not...

An anonymous social choice function for a large atomless population maps cross-section distributions of preferences into outcomes. Because any one individual is too insignificant to affect these distributions, every anonymous social choice function is individually strategy-proof. However, not...

Can mechanism design save democracy? We propose a simple design that offers a chance: individuals pay for as many votes as they wish using a number of "voice credits" quadratic in the votes they buy. Only quadratic cost induces marginal costs linear in votes purchased and thus welfare optimality...

Mechanisms for Nash implementation in the literature are fragile in the sense that they fail if just one or two players do not follow their equilibrium strategy. A mechanism is outcome-robust if its equilibrium outcome is not affected by any deviating minority of players. Is Nash implementation...

We study a multi-dimensional collective decision under incomplete information. Agents have Euclidean preferences and vote by simple majority on each issue (dimension), yielding the coordinate-wise median. Judicious rotations of the orthogonal axes -- the issues that are voted upon -- lead to...

For any linear transformation and two convex closed sets, we provide necessary and sufficient conditions for when the transformation of the intersection of the sets coincides with the intersection of their images. We also identify analogous conditions for non-convex sets, general...

This study explores mechanism design with allocation-based social preferences. Agents' social preferences and private payoffs are all subject to asymmetric information. We assume quasi-linear utility and independent types. We show how the asymmetry of information about agents' social preferences...

A mechanism is unsafe if a small number of agents deviating unexpectedly can make the mechanism deliver an outcome regarded as bad by a large number of other agents. Under Nash behavior, the direct approach of designing mechanisms with only safe Nash equilibria is impossible in many...

This paper considers the problem faced by a political authority that has to design a legislative mechanism that guarantees the selection of policies that are stable, efficient, and inclusive in the sense of strategically protecting minority interests. Experimental studies suggest that some of...