We analyze a model of multi-period monopoly in durable goods. Taking into consideration the special conditions of software markets, we assume that there are no used software markets and that manufacturers stop selling older software when they introduce a replacement model. We show that nominal...

This paper analyzes the profitability of vertical integration for an upstream monopoly facing a potential competitor. We show that it depends on the technology used by the firm when it integrates. We distinguish two types of technologies : standard technologies used by non-integrated firms, and...

In a model of horizontal product differentiation, we show that local monopolied may exist under free entry when capital is perfectly mobile. In contrast both with the situation of restricted entry and with the zero-profit approach to free entry outcomens of Salop 91979), the unit profit rate of...