The legal monopoly granted by the patent system has often been criticized for its inefficiency, which is exacerbated by … the peculiarities of knowledge as a public good. In this paper we aim at studying more deeply the latter concern. Hence we … description of the formation of knowledge externalities. In our framework a benevolent government buys immediately new patents in …

We analyze recent contributions to growth theory based on the model of expanding variety of Romer [Romer, P. (1990 … such applications, a key role is played by complementarities in the process of innovation. …