Uniqueness of Cournot Equilibrium: New Results from Old Methods

Abstract

This paper provides sufficient conditions for the existence of a unique Cournot equilibrium. Previous uniqueness results have depended on an assumption of non-degeneracy of equilibrium. As we illustrate, this assumption often fails in multi-stage games with proper Cournot subgames. Since our uniqueness results do not depend on this assumption, they are more widely applicable.