High Quality Content by WIKIPEDIA articles! Andreu Mas-Colell (Catalan: , born June 29, 1944) is a Spanish Catalan economist, an expert in microeconomics and one of the world`s leading mathematical economists. He is the founder of the Barcelona Graduate School of Economics and a professor in the department of economics at Pompeu Fabra University in Barcelona, Catalonia, Spain. He has also served several times in the cabinet of the Catalonian government. Summarizing his and others research in general equilibrium theory, his monograph gave a thorough exposition of research using differential topology. His textbook on microeconomics is the most used graduate microeconomics textbook in the world.