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.
Johann Euler Johann Albrecht Euler (27 November 1734 – 17 September 1800) was a Swiss-Russian astronomer and mathematician. Also known as "Johann Albert Euler" or "John-Albert Euler", he was the first child born to the great Swiss mathematician Leonhard Euler (1707–1783), who had emigrated [for the first time] to Saint-Petersburg on 17 May 1727. His mother was Katharina Gsell (1707–1773) whose maternal grandmother was the famous scientific illustrator Maria Sibylla Merian (1647–1717) and whose father was the Swiss Baroque painter Georg Gsell (1673–1740) who had emigrated to Russia in 1716. Katharina married Leonhard Euler on 7 January 1734 and Johann Albert would be the eldest of their 13 children (only 5 of whom survived childhood).