General Equilibrium Concepts Under Imperfect Competition: a Cournotian Approach∗
General Equilibrium Concepts under Imperfect Competition: A Cournotian Approach∗ Claude d'Aspremont,y Rodolphe Dos Santos Ferreiraz and Louis-Andr´eG´erard-Varetx Received May 14, 1993; revised March 21, 1996 Abstract In a pure exchange economy we propose a general equilibrium concept under imperfect competition, the \Cournotian Monopolistic Competition Equilibrium", and compare it to the Cournot-Walras and the Monopolistic Competition concepts. The advantage of the proposed concept is to require less computational ability from the agents. The comparison is made first through a simple example, then through a more abstract concept, the P -equilibrium based on a general notion of price coordination, the pricing-scheme. Journal of Economic Literature Classification Numbers: D5, D43 ∗Reprinted from Journal of Economic Theory, 73, 199{230, 1997. Financial Support from the European Commission HCM Programme and from the Belgian State PAI Programme (Prime Minister's Office, Science Policy Programming) is gratefully acknowledged. yCORE, Universit´ecatholique de Louvain, 34 voie du Roman Pays, 1348-Louvain-la-Neuve, Belgium zBETA, Universit´eLouis Pasteur, 38 boulevard d'Anvers, 67000-Strasbourg, France xGREQE, Ecole des Hautes Etudes en Sciences Sociales, F-13002-Marseille, France. 1 1 Introduction The formal simplicity of general equilibrium theory under perfect competition and of its assump- tions on the individual agents' characteristics, can easily be contrasted with the complexity and the ad hoc assumptions of the general analysis of imperfect competition. However the simplic- ity of general competitive analysis is all due to a single behavioral hypothesis, namely that all sellers and buyers take prices as given. This price-taking hypothesis allows for a clear notion of individual rationality, based on the simplest form of anticipations (rigid ones) and an exoge- nous form of coordination (the auctioneer).
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