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...

In an exchange economyw ith a finite number of indivisible goods, we analyze a dynamic trading process of coalitional recontracting where agents may make mistakes with small probability. We show first that the recurrent classes of the unperturbed (mistakefree) process consist of (i) all core...

Define the riskiness of a gamble as the reciprocal of the absolute risk aversion (ARA) of an individual with constant ARA who is indifferent between taking and not taking that gamble. We characterize this index by axioms, chief among them a “duality” axiom which, roughly speaking, asserts...

We view achieving a particular correlated equilibrium distribution for a normal form game as an implementation problem. We show, using a parametric version of the two-person Chicken game and a wide class of correlated equilibrium distributions, that a social choice function that chooses a...

It is well known that a social choice function is truthfully implementable in Bayesian Nash equilibrium if and only if it is incentive compatible. However, in general it is not possible to rule out other equilibrium outcomes, and additional conditions, e.g., Bayesian monotonicity, are needed to...

We apply stochastic stability to study the evolution of bidding behavior in private-values second-price, first-price and k-double auctions. The learning process has a strong component of inertia but with a small probability, the bids are modified in the direction of ex-post regrets. We identify...

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...