We introduce a description of the power structure which is inherent in a strategic game form using the concept of an interaction sheaf. The latter assigns to each open set of outcomes a set of interaction arrays, specifying the changes that coalitions can make if outcome belongs to this open...

We study the structure of unstable local effectivity functions defined for n players and p alternatives. A stability index based on the notion of cycle is introduced. In the particular case of simple games, the stability index is closely related to the Nakamura Number. In general it may be any...

1. Introduction -- 1. Collective decisions and power structure -- 2. Social choice -- 3. Games and game forms -- 4. The effectivity functions of a game form -- 5. Effectivity functions and cooperative games -- 6. An overview of the book -- 7. Notes -- 2. The structure of effectivity functions --...