Thus, strategy—in the sense in which I am using it here—is not concerned with the efficient application of force but with the exploitation of potential force. It is concerned not just with enemies who dislike each other but with partners who distrust or disagree with each other. It is concerned not just with the division of gains and losses between two claimants but with the possibility that particular outcomes are worse (better) for both claimants than certain other outcomes. In the terminology of game theory, most interesting international conflicts are not “constant-sum games” but “variable-sum games”: the sum of the gains of the participants involved is not fixed so that more for one inexorably means less for the other. There is a common interest in reaching outcomes that are mutually advantageous.

DEFINE: Defines the key game-theory distinction between constant-sum and variable-sum games, where variable-sum games involve mutual gains.

Thomas C. Schelling, The Strategy of Conflict, loc. 20