Internal hierarchy and stable coalition structures

In deciding whether to join a coalition or not, an agent must consider both i) the expected power of the coalition and ii) her position in the vertical structure within the coalition. We establish the existence of a positive relationship between the degree of inequality in remuneration within coalitions and the number of coalitions to be formed endogenously in stable systems. We show that such coalitions can be mixed and balanced, rather than segregated, in terms of members' ability levels. In any stable system each coalition is of an efficient size and every agent is paid her marginal contribution.