Cartel Stability under an Optimal Sharing Rule

Previous work on the formation and stability of cartels has focused on the case of identical players. This assumption is very restrictive in many economic environments. This paper analyses stability of cartels in games with heterogeneous players and spillovers to non-members. I introduce a sharing rule for coalition payoffs, called "optimal sharing" which stabilises all cartels that are possibly stable under any rule. Under optimal sharing the grand coalition is the unique stable cartel if spillovers are negative. I introduce a new property, called "non-essentiality" and determine the set of stable cartels under optimal sharing if spillovers are positive and if the non-essentiality property applies. Finally I analyse cartel stability under optimal sharing in simple public goods game with heterogeneous players. My results show – in contrast to earlier findings for identical players – that large coalitions may well be stable.Cartel stability, Coalition formation games with spillovers, Partition function approach, Optimal sharing rule

Sequential Sharing Rules for River Sharing Problems

We analyse the redistribution of a resource among agents who have claims to the resource and who are ordered linearly. A well known example of this particular situation is the river sharing problem. We exploit the linear order of agents to transform the river sharing problem to a sequence of two-agent river sharing problems. These reduced problems are mathematically equivalent to bankruptcy problems and can therefore be solved using any bankruptcy rule. Our proposed class of solutions, that we call sequential sharing rules, solves the river sharing problem. Our approach extends the bankruptcy literature to settings with a sequential structure of both the agents and the resource to be shared. In the paper, we first characterise a class of sequential sharing rules. Subsequently, we apply sequential sharing rules based on four classical bankruptcy rules, assess their properties, and compare them to four alternative solutions to the river sharing problem.River Sharing Problem, Sequential Sharing Rule, Bankruptcy Problem, Water Allocation

Sticks and Carrots for the Design of International Climate Agreements with Renegotiations

This paper examines stability of international climate agreements for carbon abatement under an optimal transfer rule and renegotiations. The optimal transfer rule suggested to stabilise international environmental agreements (Weikard 2005, Carraro, Eyckmans and Finus 2006) is no longer optimal when agreements are renegotiated. We determine the conditions for optimal self-enforcing sequences of agreements. If these conditions are met, then transfer payments can be arranged such that no country wants to change its membership status at any stage. In order to demonstrate the applicability of our condition we use the STACO model, a 12-regions global model, to assess the impact of welldesigned transfer rules on the stability of an international climate agreement. Although there are strong free-rider incentives, we find a stable grand coalition in the first commitment period in a game with one round of renegotiations.Stability of Coalitions, International Environmental Agreements, Partition Function Approach, Sharing Rules, Optimal Transfers, Renegotiations

Amartya Sens Beitrag zu den Wirtschaftswissenschaften: Anmerkungen zum Nobelpreis 1998

Den diesjährigen Nobelpreis für Wirtschaftswissenschaften hat der Inder Amartya Sen für seine grundlegenden Beiträge zur Wohlfahrtsökonomik, zur Einkommensverteilung und zur Analyse von Hunger und Armut erhalten. Einen Überblick über die Arbeiten von Amartya Sen gibt Dr. Hans-Peter Weikard. --

PATH-DEPENDENCE WITHOUT INCREASING RETURNS TO SCALE AND NETWORK EXTERNALITIES

Research Methods/ Statistical Methods,

The Role of Proactive Adaptation in International Climate Change Mitigation Agreements

This paper investigates the role of proactive adaptation in international mitigation coalition formation. Adaptation is introduced into a three stage cartel game of coalition formation. We analytically derive the optimal level of mitigation and proactive adaptation for the singletons and coalition members. We introduce the AD-STACO model which is constructed based on the STACO model, which is an applied three-stage cartel formation model with 12 heterogenous regions. Simulating all possible coalitions (4084) and checking for internal and external stability, we investigate how different levels of proactive adaptation will affect the payoffs in Grand coalition and the incentives to freeride. We examine which stable coalitions are found with different levels of proactive adaptation and whether regions can gain from overadaptation in the best performing stable coalition. We find that though payoffs increase in the Grand coalition with lower adaptation, incentives to leave increase. Coalition members can increase their payoffs through overadaptation.N/A

The Impact of Surplus Sharing on The Stability of International Climate Agreements

This paper analyses stability of coalitions for greenhouse gas abatement for different sharing rules applied to the gains from co-operation. We use a 12-regions model designed to examine internal and external stability of coalitions (STACO). We compare different sharing rules like, for example, grandfathering (i.e. sharing proportional to emissions) and a number of so-called equitable rules like, for example, sharing proportional to population or according to historical responsibilities. Due to strong free-rider incentives we find only small stable coalitions for all sharing rules examined. As a general pattern we observe that coalitions consist of regions with low marginal abatement costs, which are attractive partners in any coalition, and regions which have the highest claims according to the respective sharing rule. Furthermore, we find that a grandfathering scheme leads to the largest and – in terms of greenhouse gas abatement – most successful coalition, while many of the equitable rules achieve very little.International environmental agreements, Sharing rules, Stability of coalitions

The two-stage game approach to coalition formation: Where we stand and ways to go

Coalition formation is often analysed in an almost non-cooperative way, as a two-stage game that consists of a first stage comprising membership actions and a second stage with physical actions, such as the provision of a public good. We formalised this widely used approach for the case where actions are simultaneous in each stage. Herein, we give special attention to the case of a symmetric physical game. Various theoretical results, in particular, for cartel games, are provided. As they are crucial, recent results on the uniqueness of coalitional equilibria of Cournot-like physical games are reconsidered. Various concrete examples are included. Finally, we discuss research strategies to obtain results about equilibrium coalition structures with abstract physical games in terms of qualitative properties of their primitives.</p

Composition properties in the river claims problem

In a river claims problem, agents are ordered linearly, and they have both an initial water endowment as well as a claim to the total water resource. We provide characterizations of two solutions to this problem, using Composition properties which have particularly relevant interpretations for the river claims problem. Specifically, these properties relate to situations where river flow is uncertain or highly variable, possibly due to climate change impacts. The only solution that satisfies all Composition properties is the `Harmon rule' induced by the Harmon Doctrine, which says that agents are free to use any water available on their territory, without concern for downstream impacts. The other solution that we assess is the `No-harm rule', an extreme interpretation of the no-harm principle from international water law, which implies that water is allocated as far downstream as possible. In addition to characterizing both solutions, we show their relation to priority rules and sequential sharing rules