Eugene Dynkin — math (dynkin diag) with roots in the USSR
Eugene Dynkin was a Soviet-American mathematician born in Leningrad who made foundational contributions to probability theory and algebra. His Dynkin diagrams — used to classify Lie algebras — became standard tools in mathematics and physics, and his work on Markov processes shaped modern probability theory.
Tracing the roots — Leningrad
Born in Leningrad in 1924 and educated at Moscow State University, Dynkin was part of the extraordinary generation of Soviet mathematicians who operated within a system that simultaneously produced world-class science and persecuted its practitioners. He emigrated to the United States in 1977 and joined Cornell University.
Leningrad. At the time, this region was one of the fifteen republics of the Soviet Union.