We analyze the problem of fully implementing a social choice set in ex post equilibrium. We identify an ex post monotonicity condition that is necessary and - in economic environments - sufficient for full implementation in ex post equilibrium. We also identify an ex post monotonicity no veto...

The mechanism design literature assumes too much common knowledge of the environment among the players and planner. We relax this assumption by studying implementation on richer type spaces. We ask when ex post implementation is equivalent to interim (or Bayesian) implementation for all possible...

A universal type space of interdependent expected utility preference types is constructed from higher-order preference hierarchies describing (i) an agent's (unconditional) preferences over a lottery space; (ii) the agent's preference over Anscombe-Aumann acts conditional on the unconditional...

We study agents whose expected utility preferences are interdependent for informational or psychological reasons. We characterize when two types can be strategically distinguished in the sense that they are guaranteed to behave differently in some finite mechanism. We show that two types are...

Consider the following "informational robustness" question: what can we say about the set of outcomes that may arise in equilibrium of a Bayesian game if players may observe some additional information? This set of outcomes will correspond to a solution concept that is weaker than equilibrium,...

The set of outcomes that can arise in Bayes Nash equilibria of an incomplete information game where players may have access to additional signals beyond the given information structure is equivalent to the set of a version of incomplete information correlated equilibrium which we dub Bayes...

The mechanism design literature assumes too much common knowledge of the environment among the players and planner. We relax this assumption by studying implementation on richer type spaces, with more higher order uncertainty. We study the "ex post equivalence" question: When is interim...

We propose an incomplete information analogue of rationalizability. An action is said to be belief-free rationalizable if it survives the following iterated deletion process. At each stage, we delete actions for a type of a player that are not a best response to some conjecture that puts weight...

This essay is the introduction for a collection of papers by the two of us on "Robust Mechanism Design" to be published by World Scientific Publishing. The appendix of this essay lists the chapters of the book.The objective of this introductory essay is to provide the reader with an overview of...

We consider the efficient allocation of a single good with interdependent values in a quasi-linear environment. We present an approach to modelling interdependent preferences distinguishing between "payoff types" and "belief types" and report a characterization of when the efficient allocation...