Corchón, Luis C.2009-03-122009-03-122001Economics Letters. 2001, vol. 72, nº 3, p. 397-4010165-1765https://hdl.handle.net/10016/3810In this note we consider Cournot oligopoly. Due to the consideration of several consumers and/ or technologies, the profit function is not differentiable everywhere. We show that Cournot equilibrium never occurs in outputs where profit functions are not-differentiable. This result validates the procedure of differentiating profit functions to perform comparative statics in models where profit functions are not differentiable everywhere.application/pdfeng& 2001 Elsevier Science B.V. All rights reserved.Comparative staticsDifferentiabilityresearch articleL13Economía10.1016/S0165-1765(01)00442-6open access