Of Grigory Margulis or Leonid Levin, Gregori Aleksandrovich Margulis was born first.
Gregori Aleksandrovich Margulis (Russian:    , first name often given as Gregory, Grigori or Grigory; born February 24, 1946) is a Russian-American mathematician known for his work on lattices in Lie groups, and the introduction of methods from ergodic theory into diophantine approximation. 
Leonid Anatolievich Levin ( ; Russian:    ; Ukrainian:    ; born November 2, 1948) is a Soviet-American computer scientist. 
