沙普利-斯卡夫住房市场中基于群体的非明显可操纵性
Non-obvious Manipulability with Groups in Shapley-Scarf Housing Markets
AI总结：
该研究在沙普利-斯卡夫住房市场中，将策略完备性替换为基于群体的非明显可操纵性，定义了超群体下的顶端交易循环机制类，并证明此类机制的结果具有一致性。
AI中文摘要：
在沙普利-斯卡夫住房市场中，Ma（1994）证明了顶端交易循环（TTC）是满足个体理性（IR）、帕累托有效性（PE）和策略完备性的唯一机制。我们探究当用Troyan和Morrill（2020）提出的较弱条件——非明显可操纵性（NOM）替代策略完备性时，会产生哪些其他可能的机制。我们首先表明，该较弱条件本身并无帮助：所有IR和PE机制已满足NOM。因此，我们引入新条件：基于群体的非明显可操纵性，在此条件下，每个主体知晓其所在群体其他成员的偏好，但不知晓群体外主体的偏好。该条件在所有主体属于同一群体时退化为策略完备性，在每个群体为单元素集时退化为标准NOM。此外，我们引入名为群体理性（GR）的参与条件，要求没有群体的表现差于仅在自身成员间交易的情况。随后，我们定义一类名为超群体下的顶端交易循环（TTC with super-groups）的机制，其成员满足GR、PE和基于群体的NOM。该类包含与标准TTC不同的机制，包括不具备策略完备性的机制。此外，我们证明，每个满足GR、PE和基于群体的NOM的机制，其最佳和最差情况结果与每个超群体下的TTC机制相同。
英文摘要：
In Shapley-Scarf housing markets, Ma (1994) shows that top trading cycles (TTC) is the unique mechanism satisfying individual rationality (IR), Pareto efficiency (PE), and strategy-proofness. We ask what other mechanisms become possible when strategy-proofness is replaced by a weaker condition called non-obvious manipulability (NOM), introduced by Troyan and Morrill (2020). We first show that this weaker condition does not help on its own: every IR and PE mechanism is already NOM. We therefore introduce a new condition: NOM with groups, under which each agent knows the preferences of the other members of her group, but not those of agents outside the group. This condition reduces to strategy-proofness when all agents belong to one group, and to standard NOM when every group is a singleton. Also, we introduce a participation condition called group rationality (GR), which requires that no group do worse than it would by trading only among its own members. We then define a class of mechanisms called TTC with super-groups, whose members satisfy GR, PE, and NOM with groups. The class includes mechanisms that differ from standard TTC, including mechanisms that are not strategy-proof. Furthermore, we show that every mechanism that satisfies GR, PE, and NOM with groups has the same best- and worst-case outcomes as every TTC with super-groups mechanism.
