Differential Equations
August 1967, Vol. III, No. 8

Obituary

VIKTOR VLADIMIROVICH NEMYTSKII

On August 7, 1967, in the 67th year of his life, Viktor Vladimirovich Nemytskii, an outstanding specialist in the field of differential equations and professor at Moscow State University named after M. V. Lomonosov, died suddenly.

The first scientific works of Viktor Vladimirovich date from the 1920s and were devoted chiefly to questions of set-theoretic topology. These works served as the point of departure for the subsequent investigations of V. V. Nemytskii and other scholars in the theory of nonlinear integral equations and in the qualitative theory of differential equations.

The subject matter of Viktor Vladimirovich’s research on differential equations is closely connected with the activity of the seminar on differential equations at Moscow University. This seminar was organized by V. V. Stepanov in 1930, with the close participation of V. V. Nemytskii. After the death of V. V. Stepanov, V. V. Nemytskii became the head of the seminar.

Viktor Vladimirovich created and developed a number of directions in the theory of dynamical systems: the theory of completely unstable systems, the theory of general dynamical systems, the method of Lyapunov rotating functions, the topological classification of trajectories of dynamical systems, and the classification of established regimes of automatic control systems.

In his works Viktor Vladimirovich devoted considerable attention to problems in the theory of ordinary differential equations connected with the theory of stability of motion, the theory of automatic control, and the theory of nonlinear oscillations.

Viktor Vladimirovich wrote several monographs. Special mention should be made of the book Qualitative Theory of Differential Equations, written jointly with V. V. Stepanov and published in 1947 and 1949. It is difficult to overestimate the role of this book in the formation and development of the theory of ordinary differential equations. It was the first monograph in the world literature on the qualitative theory of differential equations. In the very recent period V. V. Nemytskii and his students published an extensive monograph on the theory of Lyapunov exponents.

Viktor Vladimirovich was the author of a large number of reviews on the theory of differential and integral equations. He did extensive work for the abstracting journal Matematika as editor of the section “Ordinary Differential Equations.”

Viktor Vladimirovich trained more than 40 Candidates and Doctors of Physical and Mathematical Sciences; he was an attentive scientific adviser and a responsive person. Any young scholar always had the opportunity to meet with him and discuss scientific questions in many areas of the theory of differential equations.

The death of Viktor Vladimirovich Nemytskii is a heavy loss for Soviet mathematics and, in particular, for our journal, in whose work he took a considerable part.

N. P. Erugin, E. A. Barbashin, Yu. S. Bogdanov