The paper considers a voting model where each voter's type is her preference. The type graph for a voter is a graph whose vertices are the possible types of the voter. Two vertices are connected by an edge in the graph if the associated types are "neighbors." A social choice function is locally...

In a large economy, a first-best provison rule for a public good is robustly implementable with budget balance because no one individual alone can affect the aggregate outcome. First-best outcomes can, however, be blocked by coalitions of agents acting in concert. With a requirement of immunity...

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...

We study the relation between mechanism design and voting in public-good provision. If incentive mechanisms must satisfy conditions of coalition-proofness and robustness, as well as individual incentive compatibility, the participants' contributions to public-good provision can only depend on...

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...

We prove a general possibility result for collective decision problems where individual allocations are one-dimensional, preferences are single-peaked (strictly convex), and feasible allocation profiles cover a closed convex set. Special cases include the celebrated median voter theorem (Black...