Chapter 37 Coalition structures

Abstract

Publisher Summary The study of stable coalition structures, or more generally of coalition formation, was conducted mainly within the framework of games in coalitional form. The most commonly used stability concept is the coalition-structure core, which extends individual stability to group stability. The best-known example of social environments whose associated games have a coalition-structure core is the central assignment game (in particular the marriage game). The basic result is that the game describing the following situation has a coalition-structure core: the set of players is partitioned into two disjoint groups. Each member of one group has to be matched with one member (or more) of the second. The fact that such games have a coalition structure core implies that it is possible to pair the players in such a way that there are no two players that prefer to be together over their current partners. Like firms and local jurisdictions, political parties can also be regarded as coalitions: each party (which is characterized by its political position) is identified with the set of voters supporting it. Multiparty equilibrium is, then, a stable partition of the set of voters among the different parties.