Mathematician. Career at Centre National de la Recherche Scientifique. 1986-2012, taught at École polytechnique. 1994-2013, Director, Institut des Hautes Études Scientifiques (IHÉS). 1990-92, presided over the Société Mathématique de France and, 1995-98, European Mathematical Society. Co-Founder, EuroScience. Member, Academia Europaea and Royal Spanish Academy of Sciences. Doctor Honoris Causa, Keio University and Nankai University.