Product diﬀerentiated duopoly with a potential entrant facing a single period ﬁxed cost entry barriers is modeled as a noncooperative game. In addition to characterizing the equilibrium solutions and relating them to entry costs and product diﬀerentiation, a comparison of price and quantity competition shows that entry conditions are qualitatively sensitive to the strategic variables used in a given industry. Quantity competition appears to be more favorable for entry than price competition. The use of threats and other exclusionary tactics, such as limit pricing, decisively determine the outcome when entry costs are moderate.
Nti, Kofi O. and Shubik, Martin, "Duopoly with Differentiated Products and Entry Barriers" (1981). Cowles Foundation Discussion Papers. 812.