A Non-cooperative Foundation of Core-Stability in Positive Externality NTU-Coalition Games

We identify the core as an appealing stability concept of cooperative game theory, but argue that the non-cooperative approach has conceptual advantages in the context of economic problems with externalities. Therefore, we derive a non-cooperative foundation of core-stability for positive externality NTU-games. First, in the spirit of Hart/Kurz (1983), we develop a game that we call ?-game and show that strong Nash equilibria coalition structures in this game are identical to ?- and ?-core stable coalition structures. Second, as a by-product of the definition of the ?-game, we develop an extension called an ?-game. Finally, we compare equilibria in the ?- and ?-game with those in the ?- and ?-game of Hart and Kurz (1983).Core-stability, non-cooperative game theory, positive externality games

New Roads to International Environmental Agreements: The Case of Global Warming

We analyze with an integrated assessment model of climate change the formation of interna-tional environmental agreements (IEAs) by applying the widely used concept of inter-nal & external stability and several modifications of it. We relax the assumptions of a single agreement and open membership rule. It turns out that regional agreements are superior to a single agreement and exclusive is superior to open membership in welfare and ecological terms. Moreover, we show the importance of transfers for successful treaty-making. We relate our results to the design of current and past IEAs as well as to other issues of international policy coordination.Design of climate treaty protocol, Coalition formation, Non-cooperative game theory

Endogenous Minimum Participation in International Environmental Treaties

Many international treaties come into force only after a minimum number of countries have signed and ratified the treaty. Why do countries agree to introduce a minimum participation constraint among the rules characterising an international treaty? This question is particularly relevant in the case of environmental treaties dealing with global commons, where free-riding incentives are strong. Is a minimum participation rule a way to offset these free-riding incentives? Why do countries that know they have an incentive to free-ride accept to “tie their hands” through the introduction of a minimum participation constraint? This paper addresses the above questions by analysing a three-stage non-cooperative coalition formation game. In the first stage, countries set the minimum coalition size that is necessary for the treaty to come into force. In the second stage, countries decide whether to sign the treaty. In the third stage, the equilibrium values of the decision variables are set. At the equilibrium, both the minimum participation constraint and the number of signatories – the coalition size – are determined. This paper shows that a non-trivial partial coalition, sustained by a binding minimum participation constraint, forms at the equilibrium. This paper thus explains why in international negotiations all countries often agree on a minimum participation rule even when some of them do not intend to sign the treaty. The paper also analyses the optimal size of the minimum participation constraint.Agreements, Climate, Negotiations, Policy, Incentives

Optimal Transfers and Participation Decisions in International Environmental Agreements

The literature on international environmental agreements has recognized the role transfers play in encouraging participation in international environmental agreements (IEAs), but the few results achieved so far are overly specific and do not exploit the full potential of transfers for successful treaty-making. Therefore, in this paper, we develop a framework that enables us to study the role of transfers in a more systematic way. We propose a design for transfers using both internal and external financial resources and making “welfare optimal agreements” self-enforcing. To illustrate the relevance of our transfer scheme for actual treaty-making, we use a well-known integrated assessment model of climate change to show how appropriate transfers may be able to induce almost all countries into signing a self-enforcing climate treaty.Self-enforcing international environmental agreements, Climate policy, Transfers

In hunt for size: Merger formation in the oil industry

This paper analyzes the recent mergers in the oil industry. Oil is assumed to be a homogeneous good which is produced by a small number of firms with different unit costs. Merger formation is endogenously explained as a result of cooperative decisions. We show that the mergers are amongst very asymmetric firms if initial size differences are moderate. If size differences are large, however, the more efficient firms participate in the mergers, while the least efficient firms are not attractive partners and, therefore, remain independent in the post-merger market. --Asymmetric horizontal mergers,Coalition formation,Oil industry

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.Heterogeneity, Coalition, Exchanging, Refraction, Global Externalities

Coalition Formation under Uncertainty: The Stability Likelihood of an International Climate Agreement

Results derived from empirical analyses on the stability of climate coalitions are usually very sensitive to the large uncertainties associated with the benefits and costs of climate policies. This paper provides the methodology of Stability Likelihood that links uncertainty about benefits and costs of climate change to the stability analysis of coalitions in a stochastic, empirical setting. We show that the concept of Stability Likelihood improves upon the robustness and interpretation of stability analysis. Our numerical application is based on a modified version of the climate model STACO. It turns out that the only non-trivial coalition structure with a relatively high Stability Likelihood (around 25 percent) is a coalition between the European Union and Japan, though quantitative results depend especially on the variance in regional benefits from abatement.Climate change, Coalition formation, International environmental agreements, Uncertainty

Staying Together or Breaking Apart: Policy-Makers’ Endogenous Coalitions Formation in the European Economic and Monetary Union

In this paper, we analyze coordination of macroeconomic stabilization policies within the EMU by focusing, in a dynamic set-up, on asymmetries, externalities, and the existence of a multi-country context. We study how coalitions among fiscal and monetary authorities are formed and what are their effects on the stabilization of output and price. In particular, our attention is directed to study the consequences on these issues of different institutional contexts in which policy-makers may act. Among other results, we found that, in the presence of externalities, the occurrence of asymmetries is a necessary but not a sufficient condition for cooperation.Macroeconomic stabilization, EMU, coalition formation

Dynamic Effects on the Stability of International Environmental Agreements

In terms of the number of signatories, one observes both large and small international environmental agreements. The theoretical literature, based on game theory, discusses different concepts and mechanisms for the stability of coalitions and has reached the conclusion that, under farsightedness, both large and small stable coalitions can occur. In the context of a repeated game, this implies that large stable coalitions can also be sustained over time by a simple trigger mechanism, for large enough discount factors. However, if changes in time implement changes in state, this conclusion does not hold anymore: only small stable coalitions can be sustained.IEA’s, Coalitional stability, Dynamics