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

该项目的目的是提出在各种社会困境情况下实现理想结果的机制，如信息交易、公共产品提供、环境污染等。该项目最初由三名成员Muto、Yamato和Hidano组成。武藤发展了博弈论模型，并研究了合作博弈论中的解概念“稳定集”对社会困境问题的适用性。大和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了机制。然后，另外两名成员也加入了进来。东口对社会两难问题进行了统计和计量经济学研究；山村回顾了解决社会两难问题的机制的历史发展。主要研究结果总结如下：1.明确了在社会困境情境下，主体具有远见行为时的稳定设定结果。在1的成果的基础上，设计防止搭便车提供公共产品和防止信息过度生产的机制。通过实验检查机制的性能，发现代理的行为是协同的，这是意想不到的。设计新的机制，考虑到代理之间的联盟形成。检查新机制的表现，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.