THE EXISTENCE of equilibrium in Cournot oligopoly games

In the growing literature on game theory, continuous attention has beenndrawn to a theorem by Novshek (1985) on the existence of equilibrium innCournot oligopoly games. This theorem is of substantial importance becausenit gives an equilibrium in a most general setting of a Cournot model withoutnassuming convexity of firms' cost functions. Furthermore, it weakens thenassumption of concave inverse demand.nnnnnnnnnnnn n However, the proof of this theorem provided by Novshek (1985) is notnvery well clarified. In addition to this, the proof is not complete in the sensenthat it only considers situations where firms' best response correspondencesnhave continuous branches. Realizing this incompleteness, Kukushkin (1994)ngave a rigorous proof beginning with a discrete version of the Cournot model.nKukushkin's proof is a complete and satisfactory one, but unfortunatelynthere has not been an alternative proof given from a different perspectiventhan his in the existing literature. This became the main motivation for thisnthesis.n In this thesis, I provide a clarification of Novshek's original proof, discussnthe refinement by Kukushkin (1994), and give an alternative proof ofnNovshek's theorem.n