The dynamics of groups under inclusion of the aspect of solidarity can be considered to be one of the most general and fundamental problems of sociology. Society, being one of the main subjects of sociology, is constituted by interacting human individuals. However, they are not an amorphous crowd. The interaction "forces" between the individuals generated by material, emotional, and mental needs and desires with respect to different aspects of life lead to a selforganization ofstructures within society. These structures take the form of groups (i.e. ensembles of individuals with certain common objectives). Each individual will in general simultaneously belong to several groups taking the role of a nominal or leading member in each of them.