Croisssance et cycles endogènes induits par les innovations radicales et incrementales

This paper develops a model of endogenous growth where innovation can take two forms, namely radical and incremental. The latter type of innovation means that a new intermediate good is introduced in the production of the final good, thus raising productivity in a Ethier-Romer-type way. A innovation radicale means first that the level of knowledge is multiplied by a constant factor, which raises productivity in an Aghion-Howitt way, and second that the previous innovations are made obsolete. The economy is populated by a constant number of chercheurs, who may either engage in radical or innovation incremental activity. Innovation incrementale is deterministic and continuous, innovation radicale is discrete and stochastic. The market equilibrium is an allocation of the chercheurs between radical and innovation incremental. Different types of equilibria with perfect foresight are possible: fixed as well as periodic or aperiodic allocations.