Petrovskii, Ivan

Born Jan. 5 (18), 1901, in Sevsk, in what is now Briansk Oblast; died Jan. 15, 1973, in Moscow. Soviet mathematician. Academician of the Academy of Sciences of the USSR (1946; corresponding member, 1943) and a member of the academy’s presidium (from 1953). Hero of Socialist Labor (1969).

After graduating from Moscow University in 1927, Petrovskii remained there to work. He became a professor in 1933 and the university’s rector in 1951.

Petrovskii’s most important works dealt with such subjects as the theory of partial differential equations, algebraic geometry, probability theory, the qualitative theory of ordinary differential equations, and mathematical physics. He laid the foundations for the general theory of systems of partial differential equations; he singled out and studied classes of elliptic, hyperbolic, and parabolic systems. In 1937, Petrovskii showed that the solutions of elliptic systems are analytic, and in 1936 he conducted studies of the Cauchy problem for hyperbolic and parabolic systems. In 1944 he established conditions for the existence of lacunae and for the diffusion of waves and investigated the dependence of solutions of the Cauchy problem on the initial data. Petrovskii’s work in probability theory (1934) was influential in the development of the theory of random processes. In 1933 he investigated the distribution of ovals of an algebraic curve in the projective plane. The method he devised permitted him to obtain in 1949 important results in the topology of algebraic manifolds of arbitrary dimension.

Petrovskii was an honorary doctor of the Charles University in Prague (1960) and the universities of Bucharest (1962), Lund (1968), and Sofia (1972) and was an honorary foreign member of the Academy of the Socialist Republic of Rumania (1965). He became a member of the Soviet Committee for the Protection of Peace in 1955. A deputy to the sixth through eighth convocations of the Supreme Soviet of the USSR, he became a member of the Presidium of the Supreme Soviet in 1966. Petrovskii received the State Prize of the USSR in 1946 and 1952. He was awarded five Orders of Lenin, three other orders, several medals, and four foreign orders.