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...

A choice function is \textit{list rational(izable)}, if there is a fixed \textit{list} such that for each \textit{choice set}, successive comparison of the alternatives by following the \textit{list} retrieves the chosen alternative. We extend the formulation of list rationality to stochastic...