It may be advantageous to provide a variety of kinds of patent protection to heterogenous innovations. Innovations which benefit society largely through their use as building blocks to future inventions may require a different scope of protection in order to be encouraged. We model the problem...

This paper presents a model of cumulative innovation where firms are heterogeneous in their research ability. We study the optimal reward policy when the quality of the ideas and their subsequent development effort are private information. The optimal assignment of property rights must...

When innovations are heterogeneous, it may be advantageous to provide a variety of patents. By trading off patent breadth for length, it is possible that fees are not needed in the optimal policy. We present two examples. The first is a quality-ladder model, in which innovations benefit society...