Whose contributions to math came later, Eugen Slutsky or Vladimir Arnold?
Eugen Slutsky: Evgeny "Eugen" Evgenievich Slutsky ( ; ( Евге́ний Евге́ньевич Слу́цкий) 7 April [O.S. 19 April] 1880 – 10 March 1948) was a Russian/Soviet mathematical statistician, economist and political economist. Vladimir Arnold: Vladimir Igorevich Arnold (alternative spelling Arnol'd, Russian: Влади́мир И́горевич Арно́льд , 12 June 1937 – 3 June 2010) was a Soviet and Russian mathematician. Vladimir Arnold:  While he is best known for the Kolmogorov–Arnold–Moser theorem regarding the stability of integrable systems, he made important contributions in several areas including dynamical systems theory, catastrophe theory, topology, algebraic geometry, symplectic geometry, differential equations, classical mechanics, hydrodynamics and singularity theory, including posing the ADE classification problem, since his first main result—the solution of Hilbert's thirteenth problem in 1957 at the age of 19.
Vladimir Igorevich Arnold