We adopt a dynamic approach to model the behaviour of a multiproduct monopolist investing in process innovation, and either product differentiation, or product proliferation, or both. Irrespective of the number of activities appearing in the R&D portfolio, we prove that, depending on initial...

In markets where product quality is important, more than one characteristic is usually necessary for producers to define product quality. Standard theory maintains that: (i) in a duopoly there will be a quality leader no matter whether the product can incorporate one or two vertical attributes;...