Is convergence rate monotonic?

The paper aims to develop a model of nonlinear economic growth — with simple assumptions — which explains both Japan’s S -shape convergence path and the UK’s declining path toward the US between 1870–2000, and the development of other countries, as well as post-war reconstruction. According to the model, progress in stock of knowledge is formed by a quadratic formula of the relative development of follower countries.The model draws on four recent theories. Firstly, Romer’s theory, which approaches a country’s level of development by using the number of its products (Romer 1990), secondly, Jones’ idea theory with a slight modification (Jones 2004), third, the theory of quality of institutions, which determines economic performance (North 1993), and finally, the theory of physical and human capital. The first part of the paper sets up the production function, the second determines the growth rate and analyses the reconstruction path, while the third draws up model forecasts