This paper analyzes a dynamic mixed duopoly in which a profit-maximizing competitor interacts with a competitor that prices at zero (or marginal cost), with the cumulation of output affecting their relative positions over time. The modeling effort is motivated by interactions between Linux, an open-source operating system, and Microsoft’s Windows, and consequently emphasizes demand-side learning effects that generate dynamic scale economies (or network externalities).

Analytical characterizations of the equilibrium under such conditions are offered, and some comparative static and welfare effects are examined.