Evolution of behavior when duopolists choose prices and quantities

We study duopolistic competition in a di erentiated market with rms setting prices and quantities, without explicitly imposing market clearing. Unlike the commonly adopted assumption of pro t maximizing rms, we assume rm behavior to be shaped by a Dar-winian dynamic: the less tter rm imitates the tter rm and occasionally rms may experiment with a random price and/or quantity. Our two main ndings are that: (i) a market clearing outcome always belongs to the set of feasible long run outcomes, but may co-exist with non-market clearing outcomes with as well excess supply as excess demand being possible; and (ii) there exist parameter con gurations for which the only feasible outcomes imply prices above monopoly level.