Parameterized Two-Player Nash Equilibrium

Abstract. We study the problem of computing Nash equilibria in a two-player normal form game from the perspective of parameterized com-plexity. Recent results proved hardness for a number of variants, when parameterized by the support size. We complement those results, by identifying three cases in which the problem becomes fixed-parameter tractable. These cases occur in the previously studied settings of sparse games and unbalanced games as well as in the newly considered case of locally bounded treewidth games that generalizes both these two cases.