システム情報系　社会工学域　　　　　　　　　　　　　　　　　　　　　　　　    

         平成25年度　　ファカルティ・セミナー

                       (Faculty Seminar)

日　時　：　2013年7月4日(木)　　16:30-18:00

場　所　：　第三学群F棟　3F1115

講演者　：　栗野　盛光　[　ベルリン社会科学研究所  ]

司会者　：　石川　竜一郎

演　題　：　Do outside options matter in school choice? A new perspective on the efficiency vs. strategy-proofness trade-off

                           ＜ abstract ＞

This paper studies a general school choice problem in which outside options do not necessarily exist. The Gale-Shapley student-proposing deferred acceptance mechanism (DA) has played a critical role not only in theory but also in important practical applications. An important debate centers around whether it is possible to improve upon DA via alternative strategy-proof mechanisms. We show that on a general domain of preferences where all students are able to credibly rank-list their outside or pseudo-outside options, then no strategy-proof mechanism improving upon DA exists. It is however possible to construct natural subdomains allowing for positive results, where student preferences are in part induced by an exogenous hierarchy of quality tiers. We then identify maximal domains on which it is possible to improve upon DA without sacrificing strategy-proofness. These results may help better assess the underpinnings of the three-way tension among efficiency, stability, and strategy-proofness.