A general algorithm for finding the equilibrium state of an oligopoly

Under certain concavity and differentiability assumptions about supply and demand functions, there exist efficient algorithms for finding the equilibrium state of an oligopoly. This paper relaxes differentiability and shows that the resulting equilibrium is not necessarily unique, even under strict concavity assumptions. Then it describes a situation where nondifferentiability occurs naturally. Finally numerical experimentation indicates that, in the differentiable case, the proposed algorithm is at least as efficient as algorithms to be found in the recent literature.