Bimatrix games have a quasi-strict equilibrium: an alternative proof through a heuristic approach

Takao Fujimoto, N. G. A. Karunathilake, Ravindra R. Ranade

We present an alternative proof for the existence of at least one quasi-strict equilibrium in every bimatrix game. While Norde [Bimatrix games have quasi-strict equilibria. Math Prog, {85}, 35-49] uses Brouwer's fixed point theorem, we employ Kakutani's fixed point theorem for multivalued maps, and make our proof shorter, thus teachable in a couple of lecture talks. Besides our approach admits of natural economic interpretations of some technicalities used in the proof. We also explain how we get to our method of proof. In addition, it is remarked that it is possible to adopt a field more general than that of real numbers.