On the efficiency and fairness of deferred acceptance with single tie-breaking

• 成果类型: Article
• 署名作者: Han, Xiang
• 署名单位: Shanghai University of Finance & Economics
• 刊物名称: JOURNAL OF ECONOMIC THEORY
• ISSN/ISSBN: 0022-0531
• DOI: 10.1016/j.jet.2024.105842
• 发表日期: 2024
• 关键词: Indivisible object; weak priority; random allocation; Deferred acceptance with single tie-breaking; Ex-post constrained efficiency; school choice

摘要

As a random allocation rule for indivisible object allocation under weak priorities, deferred acceptance with single tie -breaking (DA-STB) is not ex -post constrained efficient. We first observe that it also fails to satisfy equal -top fairness, which requires that two agents be assigned their common top choice with equal probability if they have equal priority for it. Then, it is shown that DA-STB is ex -post constrained efficient, if and only if it is equal -top fair, if and only if the priority structure satisfies a certain acyclic condition. We further characterize the priority structures under which DA-STB is ex -post stable -and -efficient. Based on the characterized priority domains, and using a weak fairness notion called local envy -freeness, new theoretical support is provided for the use of this rule: for any priority structure, among the class of strategy -proof, ex -post stable, symmetric, and locally envy -free rules, each of the above desiderata-ex-post constrained efficiency, ex -post stability -and -efficiency, and equal -top fairness-can be achieved if and only if it can be achieved by DA-STB.