This paper studies repeated games with imperfect public monitoring where the players are uncertain both about the payoff functions and about the relationship between the distribution of signals and the actions played. We introduce the concept of perfect public ex post equilibrium (PPXE), and show that it can be characterized with an extension of the techniques used to study perfect public equilibria. We develop identifiability conditions that are sufficient for a folk theorem; these conditions imply that there are PPXE in which the payoffs are approximately the same as if the monitoring structure and payoff functions were known. Finally, we define perfect type-contingently public ex post equilibria (PTXE), which allows players to condition their actions on their initial private information, and we provide its linear programming characterization.

THIS ARTICLE EXPLAINS current editorial procedures and policies of Econometrica; it is primarily addressed to authors who plan to submit manuscripts to the journal. Section 2 deals briefly with clarity in writing and exposition. Section 3 explains our organization and how submissions are handled. Details concerning the preparation of manuscripts are covered in Section 4; Section 5 discusses the submission of Announcements and News Notes. purpose of the Econometric Society is defined in Section 1 of our Constitution: The Econometric Society is an international society for the advancement of economic theory in its relation to statistics and mathematics.... Its main object is to promote studies that aim at the unification of the theoretical-quantitative and the empirical-quantitative approach to economic problems and that are penetrated by constructive and rigorous thinking. Econometrica has no tightly controlled policy towards subject matter. No paper is rejected because it is or too quantitative, but because our membership includes economists with a variety of research interests, it is necessary that full-length contributions be prepared so that the nonspecialist is informed of what they are about and why the results are important. At the same time, no paper is rejected because it is not mathematical enough or applied, nor need papers make a methodological contribution. What is important is that the papers we publish should be interesting, original, and well crafted, and that they use whatever mathematical and/or statistical tools are appropriate for the problem at hand.

Ve consider the problem of designing a contract between a risk-averse agent and a risk-neutral principal when the agent's action is subject to moral hazard and the principal is free to propose a new contract after the agent has chosen his effort level but before the corresponding outcome is revealed.In this setting any optimal contract is equivalent to one that is "renegotiation-proof." A renegotiation-proof contract that induces the agent to choose high effort levels by promising a higher payment following good outcomes must also induce the agent to choose lower effort levels with sufficiently high probability that the contract would not be renegotiated.We show that for a range of utility functions for the agent, including exponential and logarithmic forms, the cost-minimizing renegotiation-proof contract for a given distribution of efforts is the same as the cost-minimizing contract for that distribution under commitment.Thus, the force of the renegotiation-proof constraint is not to change the way that given distributions are implemented, but rather to change which distributions are feasible.However, if the agent has constant relative risk aversion lower than one, the principal may prefer to give the agent an ex-ante rent in order to relax the renegotiation-proofness constraint, so that the optimal contract may differ from, that under commitment not only in the choice of distribution but also in the way that distribution is implemented.Our theory may shed some light on why compensation of managers and contractors is frequently insensitive to the information obtained after the relationship is terminated, and why executives have considerable discretion to adjust the riskiness of their compensation.1.

When either there are only two players or a full dimensionality condition holds, any individually rational payoff vector of a one-shot game of complete information can arise in a equilibrium of the infinitely-repeated game if players are sufficiently patient. In contrast to earlier work, mixed strategies are allowed in determining the individually rational payoffs (even when only realized actions are observable). Any individually rational payoffs of a one-shot game can be approximated by sequential equilibrium payoffs of a long but finite game of incomplete information, where players' payoffs are almost certainly as in the one-shot game. THAT STRATEGIC RIVALRY in a long-term relationship may differ from that of a one-shot game is by now quite a familiar idea. Repeated play allows players to respond to each other's actions, and so each player must consider the reactions of his opponents in making his decision. The fear of retaliation may thus lead to outcomes that otherwise would not occur. The most dramatic expression of this phenomenon is the celebrated for repeated games. An outcome that Pareto dominates the minimax point is called individually rational. The Folk Theorem asserts that any individually rational outcome can arise as a equilibrium in infinitely repeated games with sufficiently little discounting. As Aumann and Shapley [3] and Rubinstein [20] have shown, the same result is true when we replace the word Nash by (subgame) perfect and assume no discounting at all. Because the Aumann-Shapley/Rubinstein result supposes literally no discounting, one may wonder whether the exact counterpart of the Folk Theorem holds for equilibrium, i.e., whether as the discount factor tends to one, the set of equilibrium outcomes converges to the individually rational set. After all, agents in most games of economic interest are not completely patient; the no discounting case is of interest as an approximation. It turns out that this counterpart is false. There can be a discontinuity (formally, a failure of lower hemicontinuity) where the discount factor, 8, equals one, as we show in Example 3. Nonetheless the games in which discontinuities occur are quite degenerate, and, in the end, we can give a qualified yes (Theorem 2) to the question of whether the Folk Theorem holds with discounting. In particular, it always holds in two-player games (Theorem 1). This last result contrasts with the recent work of Radner-Myerson-Maskin [18] showing that, even in two-player games, the equilibrium set may not be continuous at 8 = 1 in

We develop a duopoly model in which exit occurs because of the existence of fixed costs or opportunity costs. Each firm enters the market knowing its own cost, but not that of its opponent. As times goes on, each firm becomes increasingly pessimistic about the cost of its remaining rival. The time of exit is the only strategic variable, so that our model is a of attrition. In contrast to the classic war of attrition, however, we assume that with positive probability each firm's costs may be low enough that staying in forever is a dominant strategy. Thus our model, unlike the classic one, has a unique equilibrium.

Game theory has had a deep impact on the theory of industrial organization, in a similar (but less controversial) way as the rational expectations revolution in macroeconomics. The reason it has been embraced by a majority of researchers in the field is that it imposes some discipline on theoretical thinking. It forces economists to clearly specify the strategic variables, their timing, and the information structure faced by firms. As is often the case in economics, the researcher learns as much from constructing the model (the extensive form) as from

Drew Fudenberg, and Jean Tirole, “The Fat-Cat Effect, the Puppy-Dog Ploy, and the Lean and Hungry Look”, in Industrial Organization, Oliver E. Williamson (ed.), Edward Elgar Publishing, 1990, pp. 450–455.

"Income smoothing" is the process of manipulating the time profile of earnings or earnings reports to make the reported income stream less variable. This paper builds a theory of income smoothing based on the managers' concern about keeping their position or avoiding interference, and on the idea that current performance receives more weight than past performance when one is assessing the future. When investment is added to the model, so that income reports and dividends can be set independently, we find that both dividends and income reports may be smoothed and that dividends may convey information not present in the income report.