A value for cooperative games with a coalition structure

A value for games with a coalition structure is introduced, where the rules guiding the cooperation among the members of the same coalition are different from the interaction rules among coalitions. In particular, players inside a coalition exhibit a greater degree of solidarity than they are willing to use with players outside their coalition. The Shapley value [Shapley, 1953] is therefore used to compute the aggregate payoffs of the coalitions, and the Solidarity value [Nowak and Radzik, 1994] to obtain the payoffs of the players inside each coalition.