International conference on Geometry in the Large

dedicated to the 90th birthday of Victor Toponogov

August 16 - 20, 2021

Euler International Mathematical Institute, St. Petersburg, Russia

Victor Toponogov is best known for his contribution to global Riemannian geometry. His results include the famous angle comparison and splitting theorems, two cornerstones of modern comparison geometry.
An essay on his scientific and pedagogical activities can be found in an obituary published in Russ. Math. Surv. 61, No. 2, 341-345 (2006)

Victor Toponogov (1930-2004)

Victor Andreevich Toponogov was born March 6, 1930 in the city of Tomsk (one of the oldest Siberian cities). He graduated from the department of Mechanics and Mathematics of Tomsk University in 1953 with honor and became a PhD student at the same university. His supervisor was Professor Abram I. Fet. The famous Toponogov’s comparison theorem was the subject of his first paper and of his PhD thesis defended in 1958.

In 1956, Toponogov moved to Novosibirsk where he worked till his last day for the Institute of Mathematics of the Siberian Branch of Russian Academy of Sciences. In 1968 he got his Doctor degree (a Russian equivalent for Habilitation) on “Extremal theorems for Riemannian spaces of curvature bounded from below”. He was a lecturer at Novosibirsk State University and Novosibirsk State Pedagogical University for more than 45 years. More than 15 of his students got their PhD’s, and 7 of them obtained Doctor degrees.

The angles comparison theorem for a triangle in a Riemannian manifold with curvature bounded from below by a non-negative constant remains the most popular of Toponogov’s results since it is widely used in geometry. Toponogov’s theorem on splitting a non- negatively curved Riemannian manifold containing a straight line is also well known.

In particular, Perelman used the latter theorem in his proof of the Poincare conjecture. Let us also mention one of Toponogov’s extremal theorems. The well known Myers theorem states that if the Ricci curvature of a complete Riemannian manifold is bounded from below by a positive constant, then the diameter of the manifold is not more than the diameter of the corresponding sphere. Toponogov proved: If, under hypotheses of the Myers theorem, the diameter of the manifold coincides with the same of the sphere, then the manifold is isometric to the sphere. This result is known as Toponogov’s maximal diameter theorem and was later generalized in several directions.

Victor Toponogov was a versatile person. He was a good chess player. He walked a lot in the Siberian taiga, rafting along Siberian rivers. He always had many friends.

Victor A. Toponogov passed away November 21, 2004. He is survived by his wife Lyudmila and three sons.

More details about Victor Toponogov’s life and scientific heritage may be found in his obituary published in Russ. Math. Surv. 61, No. 2, 341-345 (2006).

List of publications of Victor Toponogov