Mechanism Design for Avoiding Social Dilemma-From the Stand point of Game Theory and Experimental Economics-

本项目的目的是提出在信息交易、公共物品提供、环境污染等各种社会困境中实现理想结果的机制。该项目由武藤、大和和日野三名成员启动。武藤建立了博弈论模型，并研究了合作博弈论中解的概念“稳定集”对社会困境问题的适用性。Yamato设计了实现理想结果的机制，并通过进行实验来评估其性能。Hidano将代理人的效用及其变化纳入机制。然后，另外两名成员加入。Higuchi对社会困境问题进行了统计和计量经济学研究; Yamamuro概述了解决社会困境问题的机制的历史发展。主要研究结果如下：1.明确了社会困境情境下个体具有远见行为时的稳定集结果.在第1项结果的基础上，设计机制，防止在提供公共产品时搭便车，并防止信息生产过剩。通过实验验证了该机制的性能，并发现了代理人的联盟行为，这是没有预料到的.设计新的机制，其中考虑到联盟的形成之间的代理。检查新机制的性能，并发现它们在防止社会困境方面发挥了很好的作用。

The aim of this project is to propose mechanisms which implement desirable outcomes in various social dilemma situations such as information trading, provision of public goods, environmental pollution, etc. The project started with three members, Muto, Yamato and Hidano. Muto developed game theoretical models and studied applicability of "stable set", a solution concept in cooperative game theory, to social dilemma problems. Yamato designed mechanisms to implement desirable outcomes and evaluated their performance by conducting experiments. Hidano incorporated agents' utility and their changes into the mechanisms. Then two other members joined. Higuchi conducted statistical and econometric study of social dilemma problems ; and Yamamuro overviewed historical developments of mechanisms to solve social dilemma problems. Principal findings are summarized as follows :1. Make clear the stable set outcomes when agents behave with farsightedness in social dilemma situations.2. On the basis of the outcomes in 1, design mechanisms to prevent free-riding in provision of public goods and to prevent overproduction of information.3. Examine performance of the mechanisms by conducting experiments; and find that agents behave coalitionally, which was not expected.4. Design new mechanisms which take into account coalition formation among agents.5. Examine performance of the new mechanisms; and find that they work well to prevent social dilemmas.