%0 Journal Article %T Nash Equilibrium of a Fixed-Sum Two-Player Game %A Yoshihiro Tanaka %J American Journal of Computational Mathematics %P 346-357 %@ 2161-1211 %D 2024 %I Scientific Research Publishing %R 10.4236/ajcm.2024.143017 %X It is well established that Nash equilibrium exists within the framework of mixed strategies in strategic-form non-cooperative games. However, finding the Nash equilibrium generally belongs to the class of problems known as PPAD (Polynomial Parity Argument on Directed graphs), for which no polynomial-time solution methods are known, even for two-player games. This paper demonstrates that in fixed-sum two-player games (including zero-sum games), the Nash equilibrium forms a convex set, and has a unique expected payoff. Furthermore, these equilibria are Pareto optimal. Additionally, it is shown that the Nash equilibrium of fixed-sum two-player games can theoretically be found in polynomial time using the principal-dual interior point method, a solution method of linear programming. %K Nash Equilibrium %K Fixed-Sum Two-Player Game %K Principal-Dual Interior Point Method %U http://www.scirp.org/journal/PaperInformation.aspx?PaperID=136229