The bipartisan set:
A tournament is a complete asymmetric binary relation U over a finite set X of outcomes. To a tournament we associate a two-player symmetric zero-sum game, in which each player chooses an outcome and wins iff his outcomes beats, according to U, the one chosen by his opponent. We prove that the game has a unique mixed-strategy equilibrium. By considering the outcomes played at equilibrium we define a new solution concept for tournaments, called the Bipartisan Set.