This paper generalizes the concept of best response to coalitions of players and offers epistemic definitions of coalitional rationalizability in normal form games. The best response of a coalition is defined to be a correspondence from sets of conjectures to sets of strategies. From every best...

This paper studies costly network formation in the context of risk sharing. Neighboring agents negotiate agreements as in Stole and Zwiebel (1996), which results in the social surplus being allocated according to the Myerson value. We uncover two types of inefficiency: overinvestment in social...

We develop a model of informal risk-sharing in social networks, where relationships between individuals can be used as social collateral to enforce insurance payments. We characterize incentive compatible risk-sharing arrangements and obtain two results. (1) The degree of informal insurance is...

This paper proposes a theory of cooperation over finite horizons, focusing on public good contribution games, that implies the broadly documented feature of decreasing cooperation over time. The central assumption is that there are two types of players: those who only care about their own...

This paper considers the effect of contracting limitations in risk-sharing networks, arisingfor example from observability, verifiability, complexity or cultural constraints. Wederive necessary and sufficient conditions for Pareto efficiency under these constraints ina general setting, and we...

We investigate situations in which agents can communicate to each other only through a chain of intermediators, for example, because they have to obey institutionalized communication protocols. We assume that all involved in the communication are strategic and might want to influence the action...