RIEB Discussion Paper Series No.2019-13

Title

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

Abstract

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.

Keywords

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

JEL Classification

C72, D71, D78

Inquiries

Makoto HAGIWARA
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).