Jacques Tits

Jacques Tits (1930 to 2021) was a Belgian-born mathematician who became a French citizen in 1974 and who worked on group theory and incidence geometry. Born in Uccle, he studied at the Free University of Brussels and received his doctorate there in 1950 under Paul Libois. He held professorships at Brussels, at the University of Bonn and, from 1973, at the Collège de France in Paris, where he remained until becoming emeritus in 2000. His best known creation is the theory of buildings, combinatorial structures on which groups of Lie type act, together with the related notion of (B, N) pairs; he classified the irreducible spherical buildings of rank at least three and, with François Bruhat, developed the theory of affine buildings. He also proved the Tits alternative for linear groups and gave his name to the Tits group, the Tits metric and the Kantor-Koecher-Tits construction. He received the Wolf Prize in 1993 and shared the 2008 Abel Prize with John Griggs Thompson.