Egorov, Dmitrii

Born Dec. 10 (22), 1869, in Moscow; died Sept. 10, 1931, in Kazan. Soviet mathematician. Corresponding member of the Academy of Sciences of the USSR (1924) and honorary member of the Academy of Sciences of the USSR (1929).

A graduate of the University of Moscow (1891), Egorov was a professor there beginning in 1903. He was president of the Moscow Mathematical Society from 1922 to 1931. His works were in differential geometry, the theory of integral equations, the calculus of variations, and the theory of functions with real variables. Egorov’s theorem (1911) asserts that for any sequence of measurable functions, converging almost everywhere on a given segment, there exists a peifect set, the measure of which can be chosen as close to that of the segment as we like and such that the sequence converges uniformly on this set. This theorem served as the starting point for work in the theory of functions with real variables. The Soviet scientists N. N. Luzin, I.I . Privalov, V. V. Stepanov, I. G. Petrovskii, L. N. Sretenskii, S. P. Finikov, V. V. Golubev, and A.M . Razmadze were students of Egorov.