Boris Pavlovich Demidovich (; ; Navahrudak, March 2, 1906 – Moscow, April 23, 1977) was a Soviet/Belorussian mathematician. Family and early life Demidovich was born in a family of teachers. His father, Pavel (1871 – 1931), was able to get higher education, graduating in 1897 in Vilna; Pavel Demidovich was a teacher throughout his life, first teaching in different towns in the Minsk and Vilna Governorates, and then in Minsk; he was very attached to his family, and to Belorussian beliefs and rituals. He also recorded some anonymous literary works of the Belorussian tradition. In 1908 Pavel Demidovich was nominated member of the Imperial Officer of the Company Enthusiasts science, Anthropology at Moscow University. Demidovich's mother, Olympia Platonovna Demidovich (1876–1970), the daughter of a priest , had been a teacher too before her marriage, when she chose to retire, in order to raise their children. Boris Demidovich had three sisters, Zinaida, Evgeniia, Zoya and a younger brother, Paul. After graduating in 1923 Demidovich attended the physical-mathematical branch of the teaching faculty, that had been established in 1921, at the Belorussian State University. He obtained his degree in 1927 and was recommended to the graduate school faculty of higher mathematics, but Demidovich did not consider that a possibility and went to work in Russia instead. Professional life For four years, Demidovich served as professor of mathematics in secondary schools throughout the Smolensk and Bryansk regions. After casually reading an advertisement in a local newspaper, he moved to Moscow and in 1931, taught in a graduate school of the Research Institute of Mathematics and Mechanics at Moscow State University. At the end of this short term, he obtained the teaching chair in the Transportation and Economic Institute NKPS, and taught there at the Department of Mathematics in 1932–33. In 1933, while retaining his teaching office at T.E.I. NKPS, Demidovich was even enlisted as senior member at the Bureau of Pilot Transport construction NKPS and worked there until 1934. At the same time, in 1932, Demidovich became a post-graduate student at the Mathematical Institute, Moscow State University, after succeeding a competition. As a postgraduate, Demidovich began to work under the guidance of Andrey Nikolaevich Kolmogorov on the theory of functions of a real variable. Kolmogorov saw that Demidovich was interested in the problems of differential equations, invited him to join him in studying the qualitative theory of ordinary differential equations under the direction