Partial Strategyproofness: Relaxing Strategyproofness for the Random Assignment Problem

Abstract

We present partial strategyproofness, a new, relaxed notion of strategyproofness for studying the incentive properties of non-strategyproof assignment mechanisms. Informally, a mechanism is partially strategyproof if it makes truthful reporting a dominant strategy for those agents whose preference intensities differ sufficiently between any two objects. We demonstrate that partial strategyproofness is axiomatically motivated and that it provides a unified perspective on incentives in the assignment domain. We then apply it to derive novel insights about the incentive properties of the Probabilistic Serial mechanism and different variants of the Boston mechanism.