I am Costas Leon and this is my personal website. I am economist with research in the area of macroeconomics and time series econometrics and teaching of undergraduate courses. I am interested in the mechanisms of the business cycle, its several analytical descriptions, both linear and non-linear, and their interpretations. The issue of trend-cycle decomposition by means of new tools (e.g. singular spectrum analysis and advanced spectral estimators), the co-existence of both equilibrium and disequilibrium states and that of the spurious regressions are of great interest to me. Recently I am exploring Aritificial Intelligence and its connection, under certain conditions critically considered, to Economics as well as its implications at the social level.