The Berge equilibrium concept formalizes mutual support among players motivated by the altruistic social value orientation in games. We prove some basic results for Berge equilibria and their relations to Nash equilibria, and we provide a straightforward method for finding Berge equilibria in n-player games. We explore some specific examples, and we explain how the Berge equilibrium provides a compelling model of cooperation in social dilemmas. We show that the Berge equilibrium also explains coordination in some common interest games and is partially successful in explaining the payoff dominance phenomenon, and we comment that the theory of team reasoning provides alternative solutions to these problems.

This article determines the conditions under which theSouthern countries should act together, or separately, whilenegotiating with the North about climate change policy andabout the conditions for future Southern engagement. The papermodels the international negotiations with complete and withasymmetric information in a dynamic framework. Results showthat, depending on their characteristics, the differentplayers can obtain benefits delaying the moment of theagreement. Copyright Kluwer Academic Publishers 2004