We develop a tractable dynamic model of productivity growth and technology spillovers that is consistent with the emergence of real world empirical productivity distributions. Firms can improve productivity by engaging in in-house R\&D, or alternatively, by trying to imitate other firms'...

The optimal design of two-part tariffs is investigated in a dynamic model where two firms belonging to the same supply chain invest in R&D activities to increase the quality of the final product. It is shown that the replication of the vertically integrated monopolist's performance can be...

We analyze the impact of obsolescence of economic inventions by incorporating maintenance costsin the endogenous growth model of expanding product varieties. This contrasts with the existingliterature, which ignores maintenance costs and uses the model of quality improvements todescribe...