A note on the stability of a Cournot-Nash equilibrium: the multiproduct case with adaptive expectations

Recently, Zhang and Zhang [Zhang, A., Zhang, Y, (1996). Stability of a Cour not-Nash equilibrium: the multi-product case. Journal of Mathematical Econo mics, 26, 441-362.] have presented sufficient and necessary conditions for the asymptotical stability of dynamic multiproduct oligopolies with Cournot expectations. First, we show via a counterexample that the necessary condi tions given in that paper do not necessarily hold, and then their sufficien t conditions are extended to adaptive expectations. Simple sufficient condi tions are finally given by using special matrix norms. (C) 2000 Elsevier Sc ience S.A. All rights reserved.