In a repeated game with private information, a perfect public equilibrium (PPE) can break down if communication is not necessarily simultaneous or if players can “spy” on each others’ information. An ex post perfect public equilibrium (EPPPE) is a PPE that is ex post incentive compatible...

We endogenize social network formation and collective enforcement using a model in which players interact bilaterally and repeatedly along costly links. Cooperation is supported by the threat of collective punishments that spread through the network. Optimal networks are attainable in...

We analyze the extent to which efficient trade is possible in an ongoing relationship between impatient agents with hidden valuations (i.i.d. over time), restricting attention to equilibria that satisfy ex post incentive constraints in each period. With ex ante budget balance, efficient trade...

This article proposes a theoretical framework for studying the invention of new products when demand is uncertain. In this framework, under general conditions, the threat of ex post entry by a competitor can deter invention ex ante. Asymmetric market power in the ex post market exacerbates the...

This paper proposes a theoretical framework for studying the invention of new products when demand is uncertain. In this framework, under general conditions, the threat of ex post entry by a competitor can deter invention ex ante. Asymmetric market power in the ex post market exacerbates the...

The game-theoretic literature on collusion has been hard pressed to explain why a cartel should engage in price wars, without resorting to either impatience, symmetry restrictions, inability to communicate, or failure to optimize. This paper introduces a new explanation that relies on none of...

We study optimal contracting in team settings, featuring stylized aspects of production environments with complex tasks. Agents have many opportunities to shirk, task-level monitoring is needed to provide useful incentives, and because it is difficult to write individual performance into formal...