Detecting profitable deviations

Abstract

Rochet’s Theorem characterizes implementable allocations in a mechanism design environment in terms of cyclic monotonicity, a concept from convex analysis. In this paper, I offer an alternative approach to both the proof and interpretation of this result, based on linear duality. This duality reveals a formal relationship between incentives and detection, much like that between prices and quantities. Moreover, it allows me to extend Rochet’s Theorem and present a subdifferential characterization of implementing payments, revenue equivalence as differentiability of a value function, as well as budget-balanced implementation in terms of attributing innocence after unilateral deviations, together with other ancillary results.