Are both Sergei Sobolev and Mikhail Leonidovich Gromov members of the IHÉS in France?
Sergei Sobolev: Sergei Lvovich Sobolev (Russian: Серге́й Льво́вич Со́болев ; 6 October 1908 – 3 January 1989) was a Soviet mathematician working in mathematical analysis and partial differential equations. Mikhail Leonidovich Gromov:  He is a permanent member of IHÉS in France and a Professor of Mathematics at New York University.
i don't know