2012년 2월 5일 일요일

Jean-Pierre Benoît, Efe A. Ok, Nash implementation without no-veto power, Games and Economic Behavior

Jean-Pierre Benoît, Efe A. Ok, Nash implementation without no-veto power, Games and Economic Behavior, Volume 64, Issue 1, September 2008, Pages 51-67, ISSN 0899-8256, 10.1016/j.geb.2007.10.011. (http://www.sciencedirect.com/science/article/pii/S0899825608000080) Abstract: For a society that consists of at least three individuals, we show that a social choice rule is Maskin monotonic if and only if it is Nash implementable by means of a mechanism that is stochastic or a mechanism that contains (arbitrary) awards. In equilibrium, the mechanisms do not have any stochastic elements and do not involve any awards. Thus, loosely speaking, one can drop the no-veto power postulate from Maskin's classic theorem on Nash implementability, provided that the notion of a mechanism is suitably generalized, thereby narrowing the gap between the properties of Maskin monotonicity and Nash implementability. Moreover, using the standard notion of a mechanism, we prove that Nash implementability is equivalent to Maskin monotonicity with renegotiation: this is a pure improvement over a well-known result of Maskin and Moore [Maskin, E., Moore, J., 1999. Implementation and renegotiation, Rev. Econ. Studies 66, 39–56]. 











Bhaskar Dutta, Arunava Sen, Nash implementation with partially honest individuals

Bhaskar Dutta, Arunava Sen, Nash implementation with partially honest individuals, Games and Economic Behavior, Volume 74, Issue 1, January 2012, Pages 154-169, ISSN 0899-8256, 10.1016/j.geb.2011.07.006. (http://www.sciencedirect.com/science/article/pii/S0899825611001175) Abstract: We investigate the problem of Nash implementation in the presence of "partially honest" individuals. A partially honest player is one who has a strict preference for revealing the true state over lying when truthtelling does not lead to a worse outcome than that which obtains when lying. We show that when there are at least three individuals, all social choice correspondences satisfying No Veto Power can be implemented. If all individuals are partially honest and if the domain is separable, then all social choice functions can be implemented in strictly dominant strategies by a mechanism which does not use "integer/modulo games". We also provide necessary and sufficient conditions for implementation in the two-person case, and describe some implications of these characterization conditions. Keywords: Nash implementation; Honesty; Separable domain