Andreu Mas-Colell (Catalan: [ənˈdɾew ˈmas kuˈleʎ]; born 29 June 1944) is an economist, an expert in microeconomics and a prominent mathematical economist. 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 Catalan 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, co-authored with Michael Whinston and Jerry Green, is the most used graduate microeconomics textbook in the world.In June 2021, Spain’s Court of Auditors found that he was among those responsible for government expenditure on the unconstitutional 2017 Catalan independence referendum, and announced its intention to fine him millions of euros; one member of the court dissented, and an outcry from economists followed. Source: Wikipedia (en)