In this paper we present an inter-temporal optimization problem of a representative R&D firm that simultaneously invests in horizontal and vertical innovations. We posit that learning-by-doing makes the process of quality improvements a positive function of the number of existing technologies...

In this paper we study a basic model of economic growth where we integrate a zero-dimensional energy balance model of the Earth. The albedo of the Earth is the piecewise smooth function of the average surface temperature, thus, taking into account possible feedback effects of a higher...