We consider robust virtual implementation, where robustness is the requirement that implementation succeed in all type spaces consistent with a given payoff type space as well as with a given space of first-order beliefs about the other agents’ payoff types. This last bit, which constitutes...

We show the robustness of the Walrasian result obtained in models of bargaining in pairwise meetings. Restricting trade to take place only in pairs, most of the assumptions made in the literature are dispensed with. These include assumptions on preferences (differentiability, monotonicity,...

We come close to characterizing the class of social choice correspondences that are implementable in rationalizable strategies. We identify a new condition, which we call set-monotonicity, and show that it is necessary and almost sufficient for rationalizable implementation. Set-monotonicity is...

Implementation in iteratively undominated strategies relies on permissive conditions. However, for the sufficiency results available, authors have relied on assumptions that amount to quasilinear preferences on a numeraire. We uncover a new necessary condition that implies that such assumptions...

We assess the strength of the different conditions identified in the literature of robust mechanism design. We focus on three conditions: ex post incentive compatibility, robust monotonicity, and robust measurability. Ex post incentive compatibility has been shown to be necessary for any concept...

Watson (2002) proposes non-forcing contracts as a way to show the limitations of the mechanism design program with ex-post renegotiation (Maskin and Moore (1999)). If one takes a partial implementation approach, as Watson does, we show that non-forcing contracts do not constitute an intermediate...

We provide a characterization of virtual Bayesian implementation in pure strategies for environments satisfying no-total-indifference. A social choice function in such environments is virtually Bayesian implementable if and only if it satisfies incentive compatibility and a condition we term...

In this short paper we provide two versions of Arrow’s impossibility theorem, in a world with only one preference profile. Both versions are extremely simple and allow a transparent understanding of Arrow’s theorem. The first version assumes a two-agent society; the second version, which is...

In an extremely interesting paper, Palacios-Huerta and Volij (2004) [PV] introduce the axiomatic method to the problem of how to rank academic journals on the basis of their mutual citations. They characterize the invariant method as the only one satisfying a list of five appealing properties....

We study a strategic model of dynamic trading where agents are asymmetrically informed over common value sources of uncertainty. There is a continuum of uninformed buyers and a finite number of sellers, some of them informed. When there is only one seller, full information revelation never...