Existence of Equilibrium in Minimax Inequalities, Saddle, Points, Fixed Points, and Games without Convexity Sets

minimax inequality, saddle points, fixed points, coincidence points, discontinuity, non-quasiconcavity, non-convexity, and non-compactness

Quasicontinuity and Nash Equilibrium in Compact and Convex Games

Strong Berge equilibrium, Pareto efficiency, strong Nash equilibrium, KyFan inequality

Co-operation and Unilateral Commitment inthe Presence of Global EnvironmentalProblems

This paper focuses on the link between group co-operation and unilateral commitment of some countries in the presence of global environmental problems. We show that in case of a failure of negotiation, some countries can decide to commit unilaterally and reduce their emissions. we call this behaviour precautionary commitment.Absence of international agreement does not mean global defection from the environmental issue. we also show that the emergence of a non-co-ordinated global co-operation can result from a strategic actionfrom the members of the coalition. The insiders of the coalition create an incentive for the non-members to reduce without co-ordinating their emissions.global environmental problems; coalition; unilateralcommitment; precautionary commitment.

North-South Climate Change Negotiations:a Sequential Game with Asymmetric Information

This article determines the conditions under which theSouthern countries should act together, or separately, while negotiating with the North about climate change policy and about the conditions for future Southern engagement. The paper models the international negotiations with complete and with asymmetric information in a dynamic framework. Results show that, depending on their characteristics, the different players can obtain benefits delaying the moment of the agreement.Bargaining theory; Asymmetric information; Climate change;International cooperation.

Une approche évolutionnaire des négociations internationales en présence de problèmes environnementaux globaux

Le présent papier s'articule autour des problèmes environnementaux globaux, et se propose de lier les négociations internationales au comportement de précaution. Cela nous conduit à montrer que le comportement de précaution peut aussi bien survenir à la suite d'un échec des négociations qu'à la conclusion d'un accord. Dans le premier cas, ce comportement a moins d'impact que la coopération de tous, mais tend tout de même à réduire la portée de la défection. Dans le second cas, si un accord est signé entre un petit nombre de pays, le comportement de précaution constitue un moyen d'élargir la portée de la coopération sans déstabiliser la coalition coopérante. Nous montrons, enfin, que l'adoption de sanctions à l’encontre des pays non-coopérants ne garantit pas pour autant l'émergence d'un large mouvement de coopération.Problèmes environnementaux globaux, Coalition, Engagement unilatéral, Stratégie évolutionnaire

North-South Climate Change Negotiations:<br />a Sequential Game with Asymmetric Information

http://www.springerlink.com/openurl.asp?genre=journal&issn=0048-5829International audienceThis article determines the conditions under which theSouthern countries should act together, or separately, while negotiating with the North about climate change policy and about the conditions for future Southern engagement. The paper models the international negotiations with complete and with asymmetric information in a dynamic framework. Results show that, depending on their characteristics, the different players can obtain benefits delaying the moment of the agreement

On Coalition Formation with Heterogeneous Agents

We propose a framework to analyze coalition formation with heterogeneous agents. Existing literature defines stability conditions that do not ensure that, once an agent decides to sign an agreement, the enlarged coalition is feasible. Defining the concepts of refraction and exchanging, we set up conditions of existence and enlargement of a coalition with heterogeneous agents. We use the concept of exchanging agents to give necessary conditions for internal stability and show that refraction is a sufficient condition for the failure of an enlargement of the coalition. With heterogeneous agents we can get a situation where a group of members of an unstable coalition does not deviate, neither within the coalition nor within the extended coalition. Hence, the possibilities of agreement are richer than in the standard analysis with homogeneous agents. Examples of industrial economics are used for illustration, and an application to climate change negotiations is discussed in more detail

Bargaining with Non-Monolithic Players

This paper analyses strategic bargaining in negotiations between non-monolithic players, i.e. agents starting negotiations can split up in smaller entities during the bargaining process. We show that the possibility of scission in the informed coalition implies that it loses its information advantages. We also show that when the possibility of a scission exists the uninformed player does not focus on his or her beliefs about the strength of the informed coalition but on the proportion of weak/strong players within this coalition. Finally, our results show that the possibility of a scission reduces the incentives for the leader to propose a high offer to ensure a global agreement. We apply this framework to international negotiations on global public goods and to wage negotiations

Quasi-Transfer Continuity and Nash Equilibrium

International audienceWe introduce a new notion of continuity, called quasi-transfer continuity, and show that it is enough to guarantee the existence of Nash equilibria in compact, quasiconcave normal form games. This holds true in a large class of discontinuous games. We show that our result strictly generalizes the pure strategy existence theorem of Carmona [Carmona, G. [2009] An existence result for discontinuous games, J. Econ. Theory144, 1333–1340]. We also show that our result is neither implied by nor does it imply the existence theorems of Reny [Reny, J. P. [1999] On the existence of pure and mixed strategy Nash equilibria in discontinuous games, Econometrica67, 1029–1056] and Baye et al. [Baye, M. R., Tian, G. and Zhou, J. [1993] Characterizations of the existence of equilibria in games with discontinuous and nonquasiconcave payoffs, Rev. Econ. Studies60, 935–948]