In mechanism design, the goal is to create rules for making a decision based on the preferences of multiple parties (agents), while taking into account that agents may behave strategically. An emerging phenomenon is to run such mechanisms on a social network; for example, Facebook recently allowed its users to vote on its future terms of use. One significant complication for such mechanisms is ...

We study a more powerful variant of false-name manipulation in Internet auctions: an agent can submit multiple false-name bids, but then, once the allocation and payments have been decided, withdraw some of her false-name identities (have some of her falsename identities refuse to pay). While these withdrawn identities will not obtain the items they won, their initial presence may have been ben...

We study the assignment of indivisible objects with quotas (universities, jobs, or offices) to a set of agents (students, job applicants, or professors). Each agent receives at most one object and monetary compensations are not possible. We characterize efficient priority rules by efficiency, strategy-proofness, and reallocation-consistency. Such a rule respects an acyclic priority structure an...

We study infinitely repeated two player games with perfect information, where each period consists of two stages: one in which the parties simultaneously choose an action and one in which they can transfer money to each other. We first derive simple conditions that allow a constructive characterization of all Paretooptimal subgame perfect payoffs for all discount factors. Afterwards, we examine...

Progressivity, inequality reduction and merging-proofness are three well-known axioms in taxation. We investigate implications of each of the three axioms through characterizations of several families of taxation rules and their logical relations. We also study the preservation of these axioms under two operators on taxation rules, the so-called convexity operator and minimal-burden operator, w...

We consider private good economies with single-plateaued preferences. We show that the uniform rule is the only allocation rule satisfying indifference (in terms of welfare), strategy-proofness and no-envy. Indifference (in terms of welfare) means that if one allocation is recommended, then another allocation is recommended if and only if all agents are indifferent between these allocations.  ...

We study contracting and costly renegotiation in settings of complete, but unverifiable information, using the mechanism-design approach. We show how renegotiation activity is best modeled in the fundamentals of the mechanism-design framework, so that noncontractibility of renegotiation amounts to a constraint on the problem. We formalize and clarify the Renegotiation-Proofness Principle (RPP),...

A feasible alternative x is a strong Condorcet winner if for every other feasible alternative y there is some majority coalition that prefers x to y. Let LC (resp., ℘C) denote the set of all profiles of linear (resp., merely asymmetric) individual preference relations for which a strong Condorcet winner exists. Majority rule is the only non-dictatorial and strategy-proof social choice rule with...