What field of study did Boris Galerkin and Jakow Trachtenberg both work in?
Boris Galerkin Boris Grigoryevich Galerkin (Russian: Бори́с Григо́рьевич Галёркин , surname more accurately romanized as Galyorkin; 4 March [O.S. 20 February] 1871  – 12 July 1945), born in Polotsk, Vitebsk Governorate, Russian Empire, was a Jewish Soviet mathematician and an engineer.
Felix Gantmacher Felix Ruvimovich Gantmacher (Russian: Феликс Рувимович Гантмахер ) (23 February 1908 – 16 May 1964) was a Soviet mathematician, professor at Moscow Institute of Physics and Technology, well known for his contributions in mechanics, linear algebra and Lie group theory. In 1925–1926 he participated in seminar guided by Nikolai Chebotaryov in Odessa and wrote his first research paper in 1926.