Abstract: The student-optimal stable mechanism (DA), the most popular mechanism in school choice, is the only one that is both stable and strategy-proof. However, when DA is implemented, a student can change the schools of others without changing her own. We show that this drawback is limited: a student cannot change her classmates while remaining in the same school. We refer to this new property as local non-bossiness and use it to provide a new characterization of DA that does not rely on stability. Furthermore, we show that local non-bossiness plays a crucial role in providing incentives to be truthful when students have preferences over their colleagues. As long as students first consider the school to which they are assigned and then their classmates, DA induces the only stable and strategy-proof mechanism. There is limited room to expand this preference domain without compromising the existence of a stable and strategy-proof mechanism.
Abstract: We study the assignment of indivisible goods to individuals without monetary transfers. Previous literature has mainly focused on efficiency and individually fair assignments; consequently, egalitarian concerns have been overlooked. Drawing inspiration from the allocation of apartments in housing cooperatives—where families prioritize egalitarianism in assignments—we introduce the concept of Rawlsian assignment. We demonstrate the uniqueness, efficiency and anonymity of the Rawlsian rule. Our findings are validated using cooperative housing preference data, showing significant improvements in egalitarian outcomes over both the probabilistic serial rule and the currently employed rule.
3. Time-constrained Dynamic Mechanisms for College Admissions (joint with Li Chen and Min Zhu). arXiv: 2207.12179
Abstract: Recent literature shows that dynamic matching mechanisms may outperform the standard mechanisms to deliver desirable results. We highlight an under-explored design dimension, the time constraints that students face under such a dynamic mechanism. First, we theoretically explore the effect of time constraints and show that the outcome can be worse than the outcome produced by the student-proposing deferred acceptance mechanism. Second, we present evidence from the Inner Mongolian university admissions that time constraints can prevent dynamic mechanisms from achieving stable outcomes, creating losers and winners among students.