understanding of international relations. In each case, the payoff for Player A is represented by the first number in a cell; the payoff for Player B is represented by the second figure. Each player has three possible payoffs. Generally, the greater the level of cooperation, the greater the combined pay off Strategy I represents full cooperation; strategy II represents partial cooperation; and strategy Ill represents a situation where neither party chooses to cooperate Imposing a reciprocity constraint means that the choice of strategy is determined mutually hus, if Player A chooses to cooperate, under a reciprocity constraint, Player B will have to cooperate, If Player A chooses Strategy Ill, and not cooperate, Player B will also choose Strategy Ill Both parties know that the imposition of a reciprocity constraint limits interaction, so that options on the diagonal. as shown in Figure 2. are left available A. Pure Common-Interest Situations In game theory, this group of situations are represented as positive sum games with a single dominant strategy that leads to efficient outcomes. This optimal outcome is achievable by the parties in a stable Nash equilibrium. This category has been categorized by Thomas Schelling as a pure common interest game. As the optimal outcome is a Nash equilibrium, where the party's incentives are perfectly aligned, any implicit or explicit agreement between the parties becomes self-enforcing, in the sense that no party has an interest to deviate unilaterally. a sample pay-off matrix in such a game could take the following form: This draws heavily on Parisi, Taxonomy, supra note 4 A Nash equilibrium is a situation where no individual player can do better by changing strategy, as long as the other party does not change strategy. Thus, neither party has any incentive to change the choice made. See Cooter and Ulen, supra note 5 at 37. See Schelling supra note 5 at 886 This draws heavily on Parisi, Taxonomy, supra note 4. 7A Nash equilibrium is a situation where no individual player can do better by changing strategy, as long as the other party does not change strategy. Thus, neither party has any incentive to change the choice made. See Cooter and Ulen, supra note 5 at 37. 8 See Schelling supra note 5 at 88. 3 understanding of international relations.6 In each case, the payoff for Player A is represented by the first number in a cell; the payoff for Player B is represented by the second figure. Each player has three possible payoffs. Generally, the greater the level of cooperation, the greater the combined pay￾off. Strategy I represents full cooperation; strategy II represents partial cooperation; and strategy III represents a situation where neither party chooses to cooperate. Imposing a reciprocity constraint means that the choice of strategy is determined mutually. Thus, if Player A chooses to cooperate, under a reciprocity constraint, Player B will have to cooperate, If Player A chooses Strategy III, and not cooperate, Player B will also choose Strategy III. Both parties know that the imposition of a reciprocity constraint limits interaction, so that options on the diagonal, as shown in Figure 2, are left available. A. Pure Common-Interest Situations In game theory, this group of situations are represented as positive sum games with a single dominantstrategy that leadsto efficient outcomes. This optimal outcome is achievable by the parties in a stable Nash equilibrium.7 This category has been categorized by Thomas Schelling as a pure common interest game.8 As the optimal outcome is a Nash equilibrium, where the party’s incentives are perfectly aligned, any implicit or explicit agreement between the parties becomesself-enforcing, in the sense that no party has an interest to deviate unilaterally. A sample pay-off matrix in such a game could take the following form: