In a recent paper, Garella and Lambertini [Economic Letters 65 (1999) 245]
claim that we should distinguish between good and bad characteristics in an
alysing the incentives for a duopoly to vertically differentiate their prod
ucts. We prove here that the results obtained by the authors are false and
we show that in the context of their model, maximum differentiation should
appear whether characteristic is good or bad. (C) 2001 Elsevier Science BN.
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