In linear-city models, if firms are allowed (not allowed) to locate outside the linear city, they engage in excessive (insufficient) R&D investments from the normative viewpoint. This implies that the feasible set of locations drastically affects their investments.

We investigate a mixed duopoly, where a state-owned welfare-maximizing public firm competes against a profit-maximizing private firm. We use a Hotelling-type spatial model which represents product differentiation. We endogenize production costs by introducing cost-reducing activities. We show...