Dmitrii Sintsov
Dmitrii Matveyevich Sintsov was a Russian mathematician known for his work in the theory of conic sections and non-holonomic geometry.
He took a leading role in the development of mathematics at the National [University of Kharkiv|University of Kharkiv], serving as chairman of the Kharkiv [Mathematical Society] for forty years, from 1906 until his death at the age of 78.