We study what kind of equilibria of which mechanisms are ex post renegotiation-proof (EPRP), i.e., robust against the possibility of ex post renegotiation under a variety of renegotiation procedures, and which social choice functions are EPRP implementable. In complete information environments...

We study a mechanism design problem under the assumption that renegotiation cannot be prevented. We investigate what kind of equilibria of which mechanisms are renegotiation-proof under a variety of renegotiation procedures, and which social choice functions can be implemented in a way that is...

We study a problem of optimal auction design in the realistic case in which the players can collude both on the way they play in the auction and on their participation decisions. Despite the fact that the principal's opportunities for extracting payments from the agents in such a situation are...

We analyze the performance of various communication protocols in a generalization of the Crawford-Sobel (1982) model of cheap talk that allows for multiple receivers. We find that whenever the sender can communicate informatively with both receivers by sending private messages, she can...

We analyze the performance of various communication protocols in a generalization of the Crawford-Sobel (1982) model of cheap talk that allows for multiple receivers. We find that whenever the sender can communicate informatively with both receivers by sending private messages, she can...

We study the principal’s optimal response to collusion in an adverse selection environment. Building on the framework of Laffont and Martimort (1997, 2000) we advance it into several directions. First, unlike most of the literature, we study a stronger collusion when the agents can coordinate...