Generic Impossibility of Partial Ex Post Implementation with General Utility Functions

Abstract

This paper examines possibility of partial ex post implementation under general utility functions which is not necessarily differentiable or quasi-linear with respect to money. We deal with an interdependent-value model in which there are two agents, two alternatives and each agent receives more than two dimensional private signal. The main result of this paper is that under generic utility functions, a public decision rule must be almost constant if it can be ex post incentive compatible with some transfer rule.

Keywords: robust mechanism design, ex post equilibrium, interdependent values, multi-dimensional signals

JEL Classification: C72, D82