The efficient rate of inventive activity is well-studied in models where only one invention follows the previous one; less understood is the efficient choice of which project to work on when there is a network of inventions. We present a general and tractable model of the direction of innovation,...

A patent "pool" is an arrangement under which patent holders in a common technology commit their patents to a single holder, who then licenses them out to the original patentees and perhaps also to outsiders. The payoffs include both revenue earned as a licensor, and technology acquired by pool...