Shapley Value Decomposition

CORE DEFINITION

The Shapley value is a solution concept in cooperative game theory that allocates the total payoff of a coalition by computing each player's average marginal contribution across every possible order in which the coalition could form. The core proposition is that this allocation satisfies fairness axioms including efficiency, symmetry, and the treatment of players who add nothing, so it provides a principled way to attribute a jointly produced result to its contributors. The key qualification is that the decomposition depends on a defined baseline, since the value of a factor is measured relative to the empty coalition or another reference point.