Robust Mechanism Design

TitleRobust Mechanism Design
Publication TypeJournal Article
Year of Publication2005
AuthorsBergemann D, Morris S
Pagination - 1813
Date PublishedNovember 2005
ISBN Number0012-9682, 0012-9682
KeywordsAsymmetric and Private Information, Mechanism Design (D82), Common Knowledge
AbstractThe mechanism design literature assumes too much common knowledge of the environment among the players and planner. We relax this assumption by studying mechanism design on richer type spaces. We ask when ex post implementation is equivalent to interim (or Bayesian) implementation for all possible type spaces. The equivalence holds in the case of separable environments; examples of separable environments arise (1) when the planner is implementing a social choice function (not correspondence) and (2) in a quasilinear environment with no restrictions on transfers. The equivalence fails in general, including in some quasilinear environments with budget balance. In private value environments, ex post implementation is equivalent to dominant strategies implementation. The private value versions of our results offer new insights into the relationship between dominant strategy implementation and Bayesian implementation.