MARGULIS, GREGORI ALEKSANDROVICH

born Feb. 24, 1946, Moscow, Russia, U.S.S.R. Russian mathematician who was awarded the Fields Medal in 1978 for his contributions to the theory of Lie groups. Margulis attended Moscow State University (Ph.D., 1970). In 1978 Margulis was awarded the Fields Medal at the International Congress of Mathematicians in Helsinki, Fin., but was not allowed by the Soviet government to travel to Finland to receive the award. In 1990 Margulis immigrated to the United States. After brief appointments at Harvard University, Cambridge, Mass., and the Institute for Advanced Study, Princeton, N.J., he was appointed to a position at Yale University, New Haven, Conn. Margulis' work was largely involved in solving a number of problems in the theory of Lie groups. In particular, Margulis proved a long-standing conjecture by Atle Selberg concerning discrete subgroups of semisimple Lie groups. The techniques he used in his work were drawn from combinatorics, ergodic theory, dynamical systems, and differential geometry. Margulis' publications include Discrete Subgroups of Semisimple Lie Groups (1991).