In a voluntary partnership prisoner's dilemma, equilibrium discounted payoff at the origin of a partnership also serves as the worst feasible threat with which to sustain cooperation. In a population model, we introduce the Markov strategy and characterize neutrally stable equilibrium. We...

The option to leave unilaterally serves as a double-edged sword for cooperation in the repeated prisoner's dilemma game, so that trigger strategies that use breakup as punishment threats generically may not yield optimally sustainable social outcome in this paradigm. In this study, we construct...

When the repeated prisoner's dilemma setup is generalized to allow for a unilateral breakup, maximal efficiency in equilibrium remains an open question. With restrictions of simple symmetry with eternal mutual cooperation, defection, or (matched) alternation on the equilibrium path, we describe...

When the repeated prisoner's dilemma setup is generalized to allow for a unilateral breakup, maximal efficiency in equilibrium remains an open question. With restrictions of simple symmetry with eternal mutual cooperation, defection, or (matched) alternation on the equilibrium path, we describe...

What institutions can sustain cooperation in groups of strangers? Here we study the role of monetary systems. In an experiment, subjects sometimes needed help and sometimes could incur a cost to help an anonymous counterpart. In the absence of money, the intertemporal exchange of help, which...

We study the emergence of norms of cooperation in experimental economies populated by strangers interacting indefinitely and lacking formal enforcement institutions. In all treatments the efficient outcome is sustainable as an equilibrium. We address the following questions: can these economies...