We study coalition formation problems with general externalities. We prove that if expectations are not prudent a … stable coalitions structure can fail to exist. Under prudent expectations a stable coalition structure exists if the set of … admissible coalitions is single-lapping. This assumption also guarantees the existence of a stable and efficient coalition …

We identify the core as an appealing stability concept of cooperative game theory, but argue that the non … 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 …