Daisuke Oyama Graduate School of Economics, University of Tokyo   Hongo 7-3-1, Bunkyo-ku Tokyo, 113-0033 Japan   doyama@grad.e.u-tokyo.ac.jp   http://www.grad.e.u-tokyo.ac.jp/~doyama/           JEL Areas: C7 : Game Theory and Bargaining Theory:General D8 : Information, Knowledge, and Uncertainty: General