RIEB Discussion Paper Series No.2019-13

RIEB Discussion Paper Series No.2019-13


Double Implementation in Dominant Strategy Equilibria and Ex Post Equilibria with Private Values


We consider the implementation problem under incomplete information and private values. We investigate double implementability of (single-valued) mappings in dominant strategy equilibria and ex post equilibria. We call a mapping a "rule". We show that the notion of an ex post equilibrium is weaker than the notion of a dominant strategy equilibrium. Then, this double implementability notion is not trivial even under private values. We define a new strategic axiom that is stronger than "strategy-proofness", but weaker than "secure strategy-proofness". We call it "weak secure-strategy-proofness". We show that a rule is doubly implementable if and only if it is weakly securely-strategy-proof.


Double implementation, Dominant strategy Equilibrium, Ex post equilibrium, Weak secure-strategy-proofness, Private values

JEL Classification

C72, D71, D78


PhD Student, Department of Industrial Engineering and Economics, Tokyo Institute of Technology, JAPAN
2-12-1 Ookayama, Meguro-ku, Tokyo
152-8550 Japan

*This Discussion Paper won the Kanematsu Fellowship Prize (FY 2019).