Core-equivalence for the Nash bargaining solution

Summary. Core equivalence and shrinking of the core results are well known for economies. The present paper establishes counterparts for bargaining economies, a specific class of production economies (finite and infinite) representing standard two-person bargaining games and their continuum counterparts as coalition production economies. Thereby we get core equivalence of the Nash solution. The results reconfirm the Walrasian approach to Nash bargaining of Trockel (1996). Moreover we establish the same speed of convergence as is known from Debreu (1975) and Grodal (1975) for replicated pure exchange economies and for regular purely competitive sequences of economies, respectively.Received: 13 June 2003, Revised: 13 January 2004, JEL Classification Numbers: C71, C78, D51.This article is dedicated to Birgit Grodal, a friend since 30 years.Financial support of the DFG under grant #444 USA 111/2/03 is gratefully acknowledged.     

Bilateral bargaining, unverifiable quality, and options to return

Summary. The paper investigates an alternating-offers bargaining game between a buyer and a seller who face several trading opportunities. These items (goods or services) differ in their non-verifiable quality characteristics which gives rise to a moral hazard problem on the seller's part. For the special case of two goods, we completely characterize the set of subgame-perfect equilibria. We find that the seller always extends an option to return the good, while the buyer may suffer from this warranty. Also, qualitatively different types of equilibrium outcomes occur depending on the parameters of the model: (a) the seller may obtain a larger share of the surplus although the parties ex ante have symmetric bargaining positions, (b) the subgame-perfect equilibrium may entail inefficient trade, and (c) multiple equilibria may exist including equilibria with delay in negotiations. Finally, we analyze a situation where bargaining proceeds after the good was returned which is shown to reestablish uniqueness and efficiency of equilibrium.Received: 23 August 2001, Revised: 3 April 2003, JEL Classification Numbers: C78, L14, L15, D82. Correspondence to: Christoph LülfesmannThis paper has greatly benefitted from discussions with Avner Shaked and Timothy von Zandt. We also wish to thank Wolfgang Leininger, Zvika Neeman, Clemens Puppe, Wolfram Richter, Karl Schlag, Ilya Segal, and seminar participants in Dortmund, Bonn and Berkeley for helpful comments and discussions. Financial support by Deutsche Forschungsgemeinschaft, SFB 303 at the University of Bonn is gratefully acknowledged.     

An experimental analysis of ultimatum bargaining

There are many experimental studies of bargaining behavior, but suprisingly enough nearly no attempt has been made to investigate the so-called ultimatum bargaining behavior experimentally. The special property of ultimatum bargaining games is that on every stage of the bargaining process only one player has to decide and that before the last stage the set of outcomes is already restricted to only two results. To make the ultimatum aspect obvious we concentrated on situations with two players and two stages. In the ‘easy games’ a given amount c has to be distributed among the two players, whereas in the ‘complicated games’ the players have to allocate a bundle of black and white chips with different values for both players. We performed two main experiments for easy games as well as for complicated games. By a special experiment it was investigated how the demands of subjects as player 1 are related to their acceptance decisions as player 2.     

Correlated equilibria and local interactions

Summary This paper shows that Nash equilibria of a local-interaction game are equivalent to correlated equilibria of the underlying game.This work was done while George Mailath and Larry Samuelson were visiting the University of Bonn, whose hospitality is gratefully acknowledged. We thank Ken Binmore for helpful discussions. This is a revision of Section 2 of Mailath, Samuelson, and Shaked [6]. Financial support from the National Science Foundation and the Deutsche Forschungsgemeinschaft, Sonderforschungsbereich 303 at the University of Bonn, is gratefully acknowledged.     

Semi-unionized bargaining with endogenous membership and management opposition

This paper develops a model of open shop unions and efficient bargain, in which there is a social custom to unionize and the firms can pay wage premiums to dissuade union membership. If firms actively oppose unions, the union density turns out to be affected by changes of the product price and the reservation wage, and it is not always positively correlated with the workers' income share. Moreover, the model provides a rationale for higher union density in centralized as opposed to decentralized bargaining systems.I would like to thank Robert Boyer, Hans Peter Grüner, Roger Guesnerie, and two referees for helpful comments and suggestions. All remaining errors are mine. Financial support from the Commission of the European Communities (SPES-915028) is gratefully acknowledged.     

N-PERSON NASH BNARGAINING WITH VARIABEL THREATS*

We consider two models of n-person bargaining problems with the endogenous determination of disagreement points. In the first model, which is a direct extension of Nash's variable threat bargaining model, the disagreement point is determined as an equilibrium threat point. In the second model, the disagreement point is given as a Nash equilibrium of the underlying noncooperative game. These models are formulated as extensive games, and axiomatizations of solutions are given for both models. It is argued that for games with more than two players, the first bargaining model does not preserve some important properties valid for two-person games, e.g., the uniqueness of equilibrium payoff vector. We also show that when the number of players is large, any equilibrium threat point becomes approximately a Nash equilibrium in the underlying noncooperative game, and vice versa. This result suggests that the difference between the two models becomes less significant when the number of players is large.     

Tax schemes in a class of differential games

This paper evaluates tax schemes in a class of differential games. The results indicate that there are many tax schemes that support efficient resource usage, but each may fail to implement the targeted resource because of the multiplicity of equilibria. Since all of the equilibria are subgame perfect, it is difficult to predict which specific one arises. Care must then be taken in using a tax scheme as a remedy for the “tragedy of the commons.” The advantages of other policy instruments (including command-and-control regulation and a tradable permit system) are also discussed. I am indebted to Gerhard Sorger, Koji Shimomura, and two anonymous referees for their helpful comments. The detailed suggestions of one of the referees in particular have markedly improved the paper. Any remaining errors are mine. Partial financial support from MEXT KAKENHI(11730017, 18078004) is also gratefully acknowledged.     

Games of strategic complementarities: an application to Bayesian games

This paper provides an introduction to the theory of games of strategic complementarities, considers Bayesian games, and provides an application to global games. This paper is based on the Spanish Economic Review lecture given at the Simposio de Análisis Económico, Alicante, December 2001. Support from the Spanish Ministry of Education and Science (project SEJ2005-08263) is gratefully acknowledged.     

Insiders and outsiders in labour market models

The monopoly union model and the wage bargaining model are analysed in light of the distinction between insiders and outsiders. It is shown that a possible outcome of the wage bargaining is the wage level where all insiders keep their job, but no outsiders are taken on. In this situation, small variations in the bargaining situation of the union will not affect the wage and employment outcome. Furthermore, it may even be the case that the union does not wish a higher wage, because this would lead to lay-offs among the insiders. Thus, the monopoly union model and the bargaining model may yield the same wage and employment levels.This paper is part of the research project Wage Formation and Unemployment at SAF Center for Applied Research at the Department of Economics, University of Oslo. Comments from Michael Hoel, Andrew Oswald, Åsa Rosén, Asbjørn Rødseth and an anonymous referee on earlier drafts are gratefully acknowledged.     

The bargaining set of a large game

We study the equivalence between the Mas-Colell bargaining set and the core in the general context of TU games with a measurable space of players. In the first part of the paper, we study the problem without imposing any restriction on the class of games we consider. In the second part, we first introduce a new class of exact games, which we call thin games. For these games, we show not only that the Mas-Colell bargaining set is equal to the core, but also that it is the unique stable set in the sense of von Neumann and Morgenstern. We then study the relation between thin games, exact non-atomic market games and non-atomic convex games. Finally, by further developing “thinness” related ideas, we prove new equivalence results for a class of non-exact market games as well as a class of non-exact, non-market games.     

The optimal degree of commitment in a negotiation with a deadline

Summary. This note explores the consequences of a player's freedom of choice over his degree of commitment for the bargaining outcome. In particular, we modify the nonstationary structure of Fershtman and Seidmann (1993)'s bargaining by allowing one player to possess imperfect commitments where the degree of commitment is chosen prior to the negotiation stage. We show that a player optimally chooses an intermediate degree of irrevocability provided the costs of increasing the degree of commitment are small enough. In this case, not only an immediate agreement is reached but also the commitment is effective.Received: 18 July 2002, Revised: 20 March 2003, JEL Classification Numbers: C78.Part of this work was written while I was visiting the IAE-CSIC and the University of Essex, whose hospitalities are gratefully acknowledged. This paper has benefited from comments of seminar participants at the University of Essex, 56th European Econometric Society Meeting, 16th Annual Congress of the European Economic Association in Lausanne and the XXVI Symposium of Economic Analysis in Barcelona. I thank Vicent Calabuig and Gonzalo Olcina for very helpful comments. I am especially indebted t o Clara Ponsatí and an anonymous referee for some very detailed comments which lead to substantial improvement of the paper. I also gratefully acknowledge the financial support from Generalitat Valenciana under a postdoctoral grant.     

Maximum-likelihood based inference in the two-way random effects model with serially correlated time effects

The general case where the time specific effect in a two way model follows an arbitrary ARMA process has not been considered previously. We offer a straightforward maximum likelihood estimator for this case. Allowing for general ARMA processes raises the issue of model specification and we propose tests of the null hypothesis of no serial correlation as well as tests for discriminating between different specifications. A Monte-Carlo experiment evaluates the finite-sample properties of the estimators and test-statistics. We have benefitted from discussions with Pietro Balestra, Marc Nerlove and Peter Schmidt and comments from participants at the Ninth International Conference on Panel Data and the Econometric Society Eight World Congress. Financial support from HSFR, the Swedish Research Council for the Humanities and Soical Sciences is gratefully acknowledged.     

Unobservable Contracts as Precommitments

It is well known that signing publicly observable contracts with third parties is a means of credibly committing to certain actions and hence may yield strategic advantages. Previous work on the commitment value of unobservable contracts has been limited to normal form games and extensive form games in which only one party has the option to sign a contract. In this paper, we extend the analysis to extensive form games in which both players can sign contracts, and characterize the set of sequential equilibria. We show that any Nash equilibrium outcome of the original game in which both players receive more than their individually rational payoffs can be supported as a sequential equilibrium outcome. Therefore, delegation acts not only as a commitment device to gain advantage over the opponent, but also as a cooperative device to attain Pareto improvements over the subgame perfect equilibrium outcome. I would like to thank Atila Abdulkadiroglu, Jean-Pierre Benoit, Alberto Bisin, Boyan Jovanovic, Ehud Kalai, Giuseppe Lopomo, George Mailath, Efe Ok, Ariel Rubinstein, Andy Schotter, seminar participants at various universities and conferences, and anonymous referees for helpful comments and suggestions. Support from the Alfred P. Sloan Foundation and Program for Economic Research at Columbia University is also gratefully acknowledged.     

Monetary Rules and Deficit Shocks

Modern theory on interest rate rules is based on the representative agent framework with infinite-horizon consumers, thereby ignoring redistributions of the fiscal burden across generations due to deficit shocks. We show how the ‘Taylor principle’ relies on this restrictive assumption. In a dynamic New Keynesian general equilibrium model with overlapping generations, the existence of a unique stable rational expectations equilibrium may also occur under a passive monetary policy. However, active monetary policy is still required to stabilize the economy in response to fiscal shocks. Thanks are due to an anonymous referee, Andrea Costa, Jordi Galí and Giancarlo Marini for very useful comments and discussions. Financial support from CNR and the FIRB project is gratefully acknowledged. The usual disclaimer applies.     

The fuzzy core and the (\Pi, \beta)-balanced core

Summary. This note provides a new proof of the non-emptiness of the fuzzy core in a pure exchange economy with finitely many agents. The proof is based on the concept of -balanced core for games without side payments due to Bonnisseau and Iehlé (2003).Received: 8 May 2003, Revised: 8 August 2004, JEL Classification Numbers: D51, C71.Helpful comments of Jean-Jacques Herings and Hans Peters are gratefully acknowledged.     

Government deficits, consumption, and the price level

This paper investigates the dynamics of the price level in a continuous time monetary version of the Yaari-Blanchard overlapping generations model with capital accumulation. It is shown that there is an interaction between fiscal discipline and price stability when the government budget is intertemporally balanced. Relevant implications are that high debt and slow adjustment adversely affect both prices and capital accumulation. Received: April 2005, Accepted: November 2005 We are very grateful to Paulo Brito, the editor, and to an anonymous referee for helpful comments. We also thank seminar participants at the University of Rome for useful discussions. Financial support from MIUR is gratefully acknowledged. The usual disclaimer applies.     

Learning across games

This paper studies the learning process carried out by two agents who are involved in many games. As distinguishing all games can be too costly (require too much reasoning resources) agents might partition the set of all games into categories. Partitions of higher cardinality are more costly. A process of simultaneous learning of actions and partitions is presented and equilibrium partitions and action choices characterized. Learning across games can destabilize strict Nash equilibria even for arbitrarily small reasoning costs and even if players distinguish all the games at the stable point. The model is also able to explain experimental findings from the traveler?s dilemma and deviations from subgame perfection in bargaining games.     

Gamson's Law versus non-cooperative bargaining theory

We compare Gamson's Law, a popular empirical model of legislative bargaining, with two non-cooperative bargaining models in three players divide the dollar games in which no player has enough votes to form a winning coalition on their own. Both of the game theoretic models better organize the comparative static data resulting from changes in nominal bargaining power than does Gamson's Law. We also identify deviations from the point predictions of the non-cooperative bargaining models. Namely, proposer power is not nearly as strong as predicted under the Baron–Ferejohn model, and a significant number of bargaining rounds tend to take more than two steps under demand bargaining and more than one stage under Baron–Ferejohn, counter to the models' predictions. Regressions using the experimental data provide results similar to the field data, but fail to do so once one accounts for predictions regarding coalition composition under Gamson's Law.     

Component efficient solutions in line-graph games with applications

Recently, applications of cooperative game theory to economic allocation problems have gained popularity. We investigate a class of cooperative games that generalizes some economic applications with a similar structure. These are the so-called line-graph games being cooperative TU-games in which the players are linearly ordered. Examples of situations that can be modeled like this are sequencing situations and water distribution problems. We define four properties with respect to deleting edges that each selects a unique component efficient solution on the class of line-graph games. We interpret these solutions and properties in terms of dividend distributions, and apply them to economic situations. This research has been done while the third author was visiting Tinbergen Institute at the Free University, Amsterdam. The research is part of the Research Programme “Strategic and Cooperative Decision Making” at the Department of Econometrics. Financial support from the Netherlands Organization for Scientific Research (NWO) in the framework of the Russian-Dutch programme for scientific cooperation, is gratefully acknowledged. The third author also appreciates partial financial support from the Russian Leading Scientific Schools Fund (grant 80.2003.6) and Russian Humanitarian Scientific Fund (grant 02-02-00189a). We thank three anonymous referees for their valuable comments.     

A bargaining approach to the Owen value and the Nash solution with coalition structure

The mechanism by Hart and Mas-Colell (1996) for non-transferable utility (NTU) games is generalized so that a coalition structure among players is taken into account. The new mechanism yields the Owen value for transferable utility (TU) games with coalition structure as well as the consistent value (Maschler and Owen 1989, 1992) for NTU games with trivial coalition structure. Furthermore, we obtain a solution for pure bargaining problems with coalition structure which generalizes the Nash (1950) bargaining solution.