日時：　2016年 02月03日　（水）
時間：　１６：３０〜１８：００
場所：　３Ｆ１１１９
講演者： 川越 敏司 氏（はこだて未来大学 複雑系知能学科）
司会： 秋山 英三
演題題目：　Truth-telling and Stability in School Choice Problems with Affirmative Action: Theory and Experiment

要旨：
The paper presents an experimental study of affirmative action policies in school choice problems with focus on the minority reserve mechanism proposed  by Hafalir et al. (2012) (referred to here as the H mechanism) and  the majority quota mechanism proposed by Kojima (2012) and Matsubae (2011)  (referred to here as the KM mechanism). We examined the performance of  these mechanisms in two preference environments and found that
(1) while truth-telling is a dominant strategy in both mechanisms, the rate of its occurrence is less than 60%;
(2) the average payoff was significantly higher with the H mechanism than with the KM mechanism, as theoretically predicted;
(3) the proportion of students exhibiting justified envy was higher with the H mechanism than with the KM mechanism;
(4) a systematic pattern of deviation from the dominant strategy was observed, and it was theoretically proven that this constituted a Nash equilibrium with the KM mechanism in some environments but not with the H mechanism at all. More generally, we show that the set of stable matchings is larger with the KM mechanism than with the H mechanism. This explains the matching instability observed with the H mechanism.