It is a widely held belief that in imperfect markets the tendency to cooperate depends on the number of competitors. E.H. Chamberlin's distinction between the small group and the large group is based on this assumption. Cooperative forms of behaviour like joint profit maximization are assumed to...

The concept of a perfect equilibrium point has been introduced in order to exclude the possibility that disequilibrium behavior is prescribed on unreached subgames. (Selten 1965 and 1973). Unfortunately this definition of perfectness does not remove all difficulties which may arise with respect...