Strategy-proof mechanisms are widely used in market design. In an abstract allocation model which outside options available to agents, we prove two results that demonstrate the interplay between strategy-proofness and options. The treat deterministic random a unified way. first result proves that, for individually rational strategy-proof mechanisms, pinning down agents' probabilities of consumi...

We consider the allotment problem of homogeneous indivisible goods among agents with single-peaked and risk-averse von Neumann-Morgenstern expected utility functions. We establish that a rule satisfies coalitional strategy-proofness, same-sideness, and strong symmetry if and only if it is the uniform probabilistic rule. By constructing an example, we show that if same-sideness is replaced by re...

New methods for solving the college admissions problem with indifference are presented and characterised with a Monte Carlo simulation in a variety of simple scenarios. Based on a qualifier defined as the average rank, it is found that these methods are more efficient than the Boston and Deferred Acceptance algorithms. The improvement in efficiency is directly related to the reduced role of ran...

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 investigate the Nash equilibria of game theoretic models of network formation based on explicit consent in link formation. These so-called “consent models” explicitly take account of link formation costs. We provide characterizations of Nash equilibria of such consent models under both one-sided and two-sided costs of link formation. We relate these equilibrium concepts to link-based stabili...

We relax strategy-proofness (a form of dominant strategy implementation) by allowing “small” gains from manipulation. In 2-agent exchange economies, this relaxation is shown to have a discontinuous effect on the range of efficient rules, demonstrating a type of nonrobustness in previous impossibility results. When gains are measured with respect to a single good and preferences are linear, we c...

We consider the problem of sharing the cost of connecting a large number of agents in a network. The centralized agency elicits the target nodes that agents want to connect and charges agents based on their demands. We look for a cost-sharing mechanism that satisfies three desirable properties: Efficiency which charges agents based on the minimum total cost of connecting them in a network, Stan...

In real electronic markets, each bidder arrives and departs over time. Thus, such a mechanism that must make decisions dynamically without knowledge of the future is called an online mechanism. In an online mechanism, it is very unlikely that the mechanism designer knows the number of bidders beforehand or can verify the identity of all of them. Thus, a bidder can easily submit multiple bids (f...

Merging operators aim at defining the beliefs/goals of a group of agents from the beliefs/goals of each member of the group. Whenever an agent of the group has preferences over the possible results of the merging process (i.e., the possible merged bases), she can try to rig the merging process by lying on her true beliefs/goals if this leads to a better merged base according to her point of vie...