Unanimous Implementation: A Case for Approval Mechanisms
25 Pages Posted: 7 Feb 2016 Last revised: 1 Jul 2016
Date Written: June 30, 2016
We design the class of (indirect) Approval mechanisms which allow the players' strategies to coincide with the subsets of the outcome space. By focusing on the single-peaked domain, we prove that: a) Each of these mechanisms is characterized by a unique equilibrium outcome, and b) for almost every implementable welfare optimum (outcome of a social choice rule), including the Condorcet winner alternative, there exists an Approval mechanism that unanimously implements it. That is, Approval mechanisms help a society achieve every feasible welfare goal, and, perhaps more importantly, they promote social coherence: The implemented outcome is approved by everyone.
Keywords: Nash Implementation, Strategy-proof, Unanimity, Indirect Mechanisms
JEL Classification: C9, D71, D78, H41
Suggested Citation: Suggested Citation