The implementation problem is the problem of designing a mechanism (game form) such that the equilibrium outcomes satisfy a criterion of social optimality embodied in a social choice rule. If a mechanism has the property that, in each possible state of the world, the set of equilibrium outcomes...

We study fiscal spending by supranational unions, where participation is voluntary and countries bargain over contributions to and the allocation of a central budget. We explore the link between the allocation and nations ́contributions that occurs since bargaining power is endogenous, and...

We analyze group contests for public goods by applying the solution concept of an evolutionary stable strategy (ESS). We show that a global ESS cannot exist, because a mutant free-rider can always invade group behavior successfully. There does exist, however, a unique local ESS, which we...

We show that Ergin & Sönmez's (2006) results which show that for schools it is a dominant strategy to truthfully rank the students under the Boston mechanism, and that the Nash equilibrium outcomes in undominated strategies of the induced game are stable, rely crucially on two assumptions....

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...

We generalize the canonical problem of Nash implementation by allowing agents to voluntarily provide discriminatory signals, i.e. evidence. Evidence can either take the form of hard information or, more generally, have differential but non-prohibitive costs in different states. In such...

A jury has to choose the winner of a contest. There exists a deserving winner, whose identity is common knowledge among the jurors, but not known by the planner. Jurors may be biased in favor (friend) or against (enemy) some contestants. We study conditions on the confi?guration of the jury so...

We study a social choice model with partially honest agents, and we show that strategy-proofness is a necessary and sufficient condition to achieve secure implementation. This result provides a behavioral foundation for the rectangularity property; and it offers as a by-product a revelation...

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...

An individual may display an honesty standard which allows her to lie a little without that being harmful to her self view as an honest person. On this basis, the paper considers a society with a finite number of individuals involving partially-honest individuals and in which every individual...