Much attention has been paid in recent years to the study of the order of integration of a time series, i.e. the number of differences that are necessary to transform it into a stationary series. The relevance of the subject arises because most of time series analysis in economics and finance...

In this paper we applied the dynamic system theory to the measurement of the stability of the European process of convergence. In particular, Lyapunov’s exponents are used to verify the influence of political and economic decisions made during the creatio