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.
Nikolai Pylchykov Nikolai Dmitrievich Pilchikov (Russian: Николай Дмитриевич Пильчиков , 2 April 1857, Kharkov, Russian Empire – 19 May 1908, Kharkov, Russian Empire) was a Russian physicist, inventor, and geologist. He is known for the discovery of the photovoltaic effect, new properties of X-rays, and ways to control various mechanisms of the radio provided a basis of radio control.