 Another important concept is the core. This notion generalizes the idea that no rational party would accept an agreement that is less favorable than the disagreement point. An allocation of the total population prize is in the core if the total amount received by any coalition is at least as great as the prize this coalition could obtain on its own. Otherwise, obviously, the coalition has an incentive to “block” the agreement. Interestingly, the Shapley value is not always in the core, except for “convex games”, that is, games such that the marginal contribution of a party to a coalition increases when the coalition is bigger.