Which mathematician was the father of physicist Nikolai Borisovich Delone: Jakow Trachtenberg or Boris Delaunay?
Jakow Trachtenberg Jakow Trachtenberg (17 June 1888 – 1953) was a Jewish mathematician who developed the mental calculation techniques called the Trachtenberg system.
Symeon of Polotsk Symeon of Polotsk or Symeon Polotsky (born "Samuel Piotrowski-Sitnianowicz", Russian: Симео́н По́лоцкий; Самуи́л Петро́вский-Ситнянович; December 12, 1629, Polotsk - August 25, 1680, Moscow) was an academically-trained Baroque Belarusian-born Russian poet, dramatist, churchman, and enlightener who laid the groundwork for the development of modern Russian literature.