COWLES FOUNDATION FOR RESEARCH IN ECONOMICS
AT YALE UNIVERSITY

Box 208281
New Haven, CT 06520-8281

COWLES FOUNDATION DISCUSSION PAPER NO. 1697

Rationalizable Implementation

Dirk Bergemann and Stephen Morris

May 2009

This note studies (full) implementation of social choice functions under complete information in (correlated) rationalizable strategies. The monotonicity condition shown by Maskin (1999) to be necessary for Nash implementation is also necessary under the more stringent solution concept. We show that it is also sufficient under a mild "no worst alternative" condition. In particular, no economic condition is required.

Keywords: Implementation, Complete information, Rationalizability, Maskin monotonicity

JEL: Classification: C79, D82