The Nash-threats folk theorem with communication and approximate common knowledge in two player games

We show that the use of communications to coordinate equilibria generates a Nash-threats folk theorem in two-player games with “almost public” information. The results generalize to the n-person case. However, the two-person case is more difficult because it is not possible to sustain equilibria by comparing the reports of different players, and using these “third parties” to effectively enforce contracts.     

Iterated potential and robustness of equilibria

For any given set-valued solution concept, it is possible to consider iterative elimination of actions outside the solution set. This paper applies such a procedure to define the concept of iterated monotone potential maximizer (iterated MP-maximizer). It is shown that under some monotonicity conditions, an iterated MP-maximizer is robust to incomplete information [A. Kajii, S. Morris, The robustness of equilibria to incomplete information, Econometrica 65 (1997) 1283-1309] and absorbing and globally accessible under perfect foresight dynamics for a small friction [A. Matsui, K. Matsuyama, An approach to equilibrium selection, J. Econ. Theory 65 (1995) 415-434]. Several simple sufficient conditions under which a game has an iterated MP-maximizer are also provided.     

A belief-based approach to the repeated prisoners' dilemma with asymmetric private monitoring

This paper extends the belief-based approach to the repeated prisoners' dilemma with asymmetric private monitoring. We first find that the previous belief-based techniques [T. Sekiguchi, Efficiency in repeated prisoners' dilemma with private monitoring, J. Econ. Theory 76 (1997) 345-361; V. Bhaskar, I. Obara, Belief-based equilibria in the repeated prisoners' dilemma with private monitoring, J. Econ. Theory 102 (2002) 40-69] cannot succeed when players' private monitoring technologies are sufficiently different. We then modify the previous belief-based approach by letting the player with smaller observation errors always randomize between cooperate and defect along the cooperative path of the play. We show that with vanishing observation errors, efficiency and a folk theorem can be approximated using our modified belief-based strategies.     

Efficiency results in N player games with imperfect private monitoring

We demonstrate that efficiency is achievable in a certain class of N player repeated games with private, almost perfect monitoring. Our equilibrium requires only one period memory and can be implemented by two state automata. Furthermore, we show that this efficiency result holds with any degree of accuracy of monitoring if private signals are hemiindependent. Whereas most existing research focuses on two player cases or only a special example of N player games, our results are applicable to a wide range of N player games of economic relevance, such as trading goods games and price-setting oligopolies.     

Folk theorem with communication

This paper proves a new folk theorem for repeated games with private monitoring and communication, extending the idea of delayed communication in Compte [O. Compte, Communication in repeated games with imperfect private monitoring, Econometrica 66 (1998) 597-626] to the case where private signals are correlated.The sufficient condition for the folk theorem is generically satisfied with more than two players, even when other well-known conditions are not. The folk theorem also applies to some two-players repeated games.     

A limit characterization of belief-free equilibrium payoffs in repeated games

The present paper studies repeated games with private monitoring, and characterizes the set of belief-free equilibrium payoffs in the limit as the discount factor approaches one and the noise on private information vanishes. Contrary to the conjecture by Ely et al. [J.C. Ely, J. Hörner, W. Olszewski, Belief-free equilibria in repeated games, Econometrica 73 (2005) 377-415], the equilibrium payoff set is computed by the same formula, no matter how many players there are. As an application of this result, a version of the folk theorem is established for N-player prisoner's dilemma games.     

UNIQUENESS OF EQUILIBRIUM PAYOFFS IN FINITELY REPEATED GAMES WITH IMPERFECT MONITORING*

This paper examines when a finitely repeated game with imperfect monitoring has a unique equilibrium payoff vector. This problem is nontrivial under imperfect monitoring, because uniqueness of equilibrium (outcome) in the stage game does not extend to finitely repeated games. A (correlated) equilibrium is equilibrium minimaxing if any player's equilibrium payoff is her minimax value when the other players choose a correlated action profile from the actions played in the equilibrium. The uniqueness result holds if all stage game correlated equilibria are equilibrium minimaxing and have the same payoffs. The uniqueness result does not hold under weaker conditions.     

Local public goods, inter-regional transfers and private information

Suppose that the centre wishes to make transfers between member states of a federation to reduce inequality. However, it lacks precise information concerning the cost differences that are responsible for the initial income inequality. We examine the implications of asymmetric information for the design of the transfer scheme. We show that if member states’ inherent cost levels as local public good providers take discrete values, the first best, or ‘complete information’, transfer scheme may or may not violate incentive compatibility. If inherent cost is a continuous random variable, such a scheme certainly violates incentive compatibility. We also explore the possibility of binding participation constraints. In our model, a binding incentive compatibility constraint leads to a reduction in effort devoted to cost reduction, and a binding participation constraint will also lead to a violation of Samuelson's optimality condition for public good provision.     

Strategy-proof assignment on the full preference domain

We consider the problem of efficiently allocating several indivisible objects between agents who are to receive at most one object and whose preferences are private information. We examine this standard “assignment” problem from the perspective of mechanism design giving up the usual assumption of linear preferences and instead using a full preference domain (with indifferences permitted). We characterize two classes of mechanisms: (i) Bi-polar Serially Dictatorial Rules by Essential Single-Valuedness, Pareto Indifference, Strategy-Proofness and Non-Bossiness; and (ii) all selections from Bi-polar Serially Dictatorial Rules by Single-Valuedness, Efficiency, Strategy-Proofness and Weak Non-Bossiness. We compare the outcomes from the (Bi-polar) Serially Dictatorial Rules with the outcomes obtained using a market based approach, namely the “core” of the market. We show that all strongly efficient outcomes in the core can be generated using Serially Dictatorial Rules. Moreover, we argue that Serially Dictatorial Rules have an advantage over the market based approach in that they yield strongly efficient solutions for all preference profiles, making it possible to use randomization to restore equity. When preferences are private information, this type of ex ante equity cannot be implemented using the market based approach.     

Coordination failure in repeated games with private monitoring

Players coordinate continuation play in repeated games with public monitoring. We investigate the robustness of such equilibrium behavior with respect to ex-ante small private-monitoring perturbations. We show that with full support of public signals, no perfect public equilibrium is robust if it induces a “regular” 2×2$2\times 2$ coordination game in the continuation play. This regularity condition is violated in all belief-free equilibria. Indeed, with an individual full rank condition, every interior belief-free equilibrium is robust. We also analyze block belief-free equilibria and point out that the notion of robustness is sensitive to whether we allow for uninterpretable signals.     

Can decentralization be beneficial?

A conventional justification for government hierarchy in the fiscal federalism literature is based upon asymmetry in policy tools or in information access that is available to different levels of government. This paper demonstrates that even if these asymmetries are eliminated, addition of local (regional) governments to a one-tier central government can be strictly welfare improving.     

Old‐age Social Security versus Forward Intergenerational Public Goods Provision

This paper introduces an overlapping‐generations model with earnings heterogeneity and borrowing constraints. The labour income tax and the allocation of tax revenue between social security and forward intergenerational public goods are determined in a bidimensional majoritarian voting game played by successive generations. The political equilibrium is characterized by an ends‐against‐the‐middle equilibrium where low‐income and high‐income individuals form a coalition in favour of a lower tax rate and less social security while middle‐income individuals favour a higher tax rate and greater social security. Government spending then shifts from social security to public goods provision if higher wage inequality is associated with a borrowing constraint and a high elasticity of marginal utility of youth consumption.     

The Value of Information in the Hold-Up Problem

Abstract In the literature, the information structure of the hold‐up problem is typically assumed to be exogenous. In this paper, we introduce an additional stage at which the head office may grant individual divisions access to an information system before they undertake their specific investments. Although more information ceteris paribus enhances each divisions' profits, more information can reduce divisions' investments and destroy synergies for the other division that would have been generated by the investments. If this negative effect dominates, then information can be harmful for the entire company. Hence, information control can be a subtle force to deal with the hold‐up problem to a certain extent. In this paper we analyze those conditions under which information is either harmful or beneficial for central management.     

After you—endogenous sequencing in voluntary contribution games

We examine contributions to a public good when some donors do not know the true value of the good. If donors in such an environment determine the sequence of moves, two contribution orders may arise as equilibria. Either the uninformed and informed donors contribute simultaneously or the informed contribute prior to the uninformed. Sequential moves result in a larger provision of the public good, because the follower mimics the action of the leader, and in accounting for this response the leader chooses to contribute when it is efficient to do so. An experimental investigation of the game shows that the donors predominantly choose to contribute sequentially, and that the resulting contributions are larger than those of the simultaneous-move game. Although the gain from sequential moves is smaller when the sequence is set exogenously, our results suggest that the involved parties would benefit from having sequential moves imposed upon them.     

α‐SERIAL MECHANISMS FOR THE PROVISION OF AN EXCLUDABLE PUBLIC GOOD

We present a new class of “α‐serial mechanisms” for the provision of an excludable public good. Those mechanisms have a similar structure to the serial mechanism, but may let the non‐consumers pay a positive cost. They inherit desirable properties such as anonymity, envy‐freeness, Maskin monotonicity, and population monotonicity from the serial mechanism. We calculate the “maximal efficiency loss” and “maximal manipulation” of α‐serial mechanisms and point out a trade‐off between these two properties.     

On the endogeneity of Cournot-Nash and Stackelberg equilibria: games of accumulation

We characterize equilibria of games with two properties: (i) Agents have the opportunity to adjust their strategic variable after their initial choices and before payoffs occur; but (ii) they can only add to their initial amounts. The equilibrium set consists of just the Cournot-Nash outcome, one or both Stackelberg outcomes, or a continuum of points including the Cournot-Nash outcome and one or both Stackelberg outcomes. A simple theorem that uses agents’ standard one-period reaction functions and the one-period Cournot-Nash and Stackelberg equilibria delineates the equilibrium set. Applications include contribution, oligopoly, and rent-seeking games.     

Does hidden information make trade liberalization more fragile?

Abstract This paper focuses on the impact of hidden information on strategic interaction in the context of trade agreements. In the presence of informational asymmetry it is possible that a tradeoff between liberalization and sustainability of cooperation emerges. It is shown that it may be optimal to agree on a degree of liberalization associated with a strictly positive ex ante probability of deviation occurring. In that case, cooperation will break down in finite time, and the optimal degree of liberalization cannot be applied indefinitely.     

Information in conflicts

We consider two-player contests for a prize of common but uncertain value. For settings where one player knows the value of the prize, while the other only knows its prior distribution, we give conditions for when the uninformed agent is ex ante strictly more likely to win the prize than is the informed agent. In the special case of a lottery contest, equilibrium expenditures are lower under asymmetric information than if either both agents are informed or neither agent is informed.     

Pigouvian pricing and stochastic evolutionary implementation

We study the implementation of efficient behavior in settings with externalities. A planner would like to ensure that a group of agents make socially optimal choices, but he only has limited information about the agents’ preferences, and can only distinguish individual agents through the actions they choose. We describe the agents’ behavior using a stochastic evolutionary model, assuming that their choice probabilities are given by the logit choice rule. We prove that there is a simple price scheme with the following property: regardless of the realization of preferences, a group of agents subjected to the price scheme will spend the vast majority of time in the long run behaving efficiently. The price scheme defines a game that may possess multiple equilibria, but we are able to obtain a unique and efficient selection from this set because of the stochastic nature of the agents’ choice rule. We conclude by comparing the performance of our price scheme with that of VCG mechanisms.     

THE SECOND‐PRICE AUCTION SOLVES KING SOLOMON'S DILEMMA*

The planner wants to give k identical, indivisible objects to the top k valuation agents at zero costs. Each agent knows her own valuation of the object and whether it is among the top k. Modify the (k+ 1)st‐price sealed‐bid auction by introducing a small participation fee and the option not to participate in it. This simple mechanism implements the desired outcome in iteratively undominated strategies. Moreover, no pair of agents can profitably deviate from the equilibrium by coordinating their strategies or bribing each other.