We present a simple model of voluntary groups in a collective action problem where individuals differ in their willingness to cooperate. The heterogeneity of individuals' preferences generally yields multiple equilibrium groups with different levels of cooperation. Voluntary participation in a...

This paper studies infinitely repeated games where players can form coalitions to coordinate their actions via self-enforcing agreements. The proposed notion of "stable agreements" extends a characterization of the set of subgame perfect equilibrium paths by Greenberg (1989, 1990) to account for...

We study the infinitely repeated prisonerʼs dilemma with the option to maintain or to quit relationships. We show that if agents imitate successful strategies infrequently, defection is not dynamically stable and cooperation emerges regardless of the initial distribution of strategies.

Sequentiality of moves in an infinitely repeated prisoner's dilemma does not change the conditions under which mutual cooperation can be supported in equilibrium as compared to simultaneous decision-making. The nature of the interaction is different, however, given that the second mover in a...

I define constrained efficient direct mechanisms as those that are not Pareto dominated within the set of direct mechanisms that satisfy some given feasibility constraints – incentive compatibility and other constraints. I show a standard equivalence with maximization of a social welfare...