Renegotiation-Proof Equilibria: Collective Rationality and Intertemporal Cooperation

Cooperation in repeated games relies on the possibility that equilibrium play following some t -period history depends on more than simply the structure of the game remaining after the first t periods, that structure being always the same. In a nondegenerate theory of renegotiation, what a player expects, and the statements he finds credible at the end of period t must be affected by the history that has transpired, and perhaps by the implicit agreement that was in force. The solution concept proposed in this paper acknowledges both these influences, while imposing a certain stationarity on beliefs regarding what renegotiation options are available: renegotiation to an equilibrium sigma will not take place if, after some history h, the continuation equilibrium sigma given h is itself vulnerable to renegotiation to sigma (in the sense that all players prefer sigma to sigma given h )

Repeated Games: Cooperation and Rationality

The paper is a survey written for the Sixth World congress of the Econometric Society. It is devoted largely to a discussion of the progress made in the last decade in understanding the structure of self-enforcing agreements in discounted supergames of complete information. Perfect and imperfect monitoring models are considered in turn, with attention given to the case of substantial impatience as well as to the various “folk theorems.” The emphasis is on the features of constrained-optimal perfect equilibria, causes of inefficiency, and some relationships among different strands of the literature. The remainder of the paper is a critical and comparative consideration of recent work on renegotiation in repeated games

The Interaction of Implicit and Explicit Contracts in Repeated Agenc

Traditional agency theory assumes that the principal has no more information about the agent’s actions than the enforcement authorities have. This is unrealistic in many settings, and in repeated models, additional information possessed by the principal changes the nature of the problem. Such information can be used in implicit, self-enforcing contracts between principal and agent, that supplement the usual explicit contracts. This paper studies the way in which the two kinds of contracts are combined in constrained efficient equilibria of the agency supergame. The agent’s compensation is comprised of both guaranteed payments and voluntary bonuses from the principal. We give a simple characterization of the composition of remuneration in the optimal dynamic scheme

A Bound of the Proportion of Pure Strategy Equilibria in Generic Games

In a generic finite normal form game with 2(α) + 1 Nash equilibria, at least alpha of the equilibria are nondegenerate mixed strategy equilibria (that is, they involve randomization by some players)

Renegotiation and Symmetry in Repeated Games

It seems reasonable to suppose that in repeated games in which communications is possible, play is determined through a process of negotiation and renegotiation as events unfold. In the absence of a satisfying theory of players’ bargaining power, it is unclear how to model this process. Symmetric repeated games are an important class in which the problem is less troublesome. Whatever its source, bargaining power is presumably the same for all players in a symmetric game. We take equal bargaining power to mean that a player can mount a credible objection to a continuation equilibrium in which he receives a particular expected present discounted value, if there are other self enforcing agreements that never give any player such a low continuation value after any history. This is formalized in a solution concept called consistent bargaining equilibrium

Toward a Theory of Discounted Repeated Games with Imperfect Monitoring

This paper investigates pure strategy sequential equilibria of repeated games with imperfect monitoring. The approach emphasizes the equilibrium value set and the static optimization problems embedded in external equilibria. We characterize these equilibria, and provide computational and comparative statics results. The “self-generation” and “bang-bang” propositions which were at the core of our analysis of optimal cartel equilibria [2], are generalized to asymmetric games and infinite action spaces. New results on optimal implicit reward functions include the necessity (as opposed to sufficiency) of bang-bang functions, and the nature of optimal punishment regions

Information and Timing in Repeated Partnerships

In a repeated partnership game with imperfect monitoring, we distinguish among the effects of (1) shortening the period over which actions are held fixed, (2) increasing the frequency with which accumulated information is reported, and (3) reducing the amount of discounting of payoffs between successive periods. While reducing the amount of discounting generally improves incentives for cooperation, the other two changes can have the reverse effect. When the game is specified in the customary way with information reported at the end of each period of fixed action, the net effect of shortening the period length can be to destroy all incentives for cooperation, reversing the usual conclusion associated with the Folk Theorem for repeated games. Moreover, when interest rates are low, reducing the frequency of information reporting can greatly enhance the efficiency of equilibrium

A Bound of the Proportion of Pure Strategy Equilibria in Generic Games

In a generic finite normal form game with 2(alpha) + 1 Nash equilibria, at least alpha of the equilibria are nondegenerate mixed strategy equilibria (that is, they involve randomization by some players).Normal form, mixed strategy, game theory