Dmitri Fyodorovich Egorov (; December 22, 1869 – September 10, 1931) was a

Russian Russian(s) may refer to: *Russians (), an ethnic group of the East Slavic peoples, primarily living in Russia and neighboring countries *A citizen of Russia *Russian language, the most widely spoken of the Slavic languages *''The Russians'', a b ...

and

Soviet The Union of Soviet Socialist Republics. (USSR), commonly known as the Soviet Union, was a List of former transcontinental countries#Since 1700, transcontinental country that spanned much of Eurasia from 1922 until Dissolution of the Soviet ...

mathematician A mathematician is someone who uses an extensive knowledge of mathematics in their work, typically to solve mathematical problems. Mathematicians are concerned with numbers, data, quantity, mathematical structure, structure, space, Mathematica ...

known for contributions to the areas of

differential geometry Differential geometry is a Mathematics, mathematical discipline that studies the geometry of smooth shapes and smooth spaces, otherwise known as smooth manifolds. It uses the techniques of Calculus, single variable calculus, vector calculus, lin ...

and

mathematical analysis Analysis is the branch of mathematics dealing with continuous functions, limit (mathematics), limits, and related theories, such as Derivative, differentiation, Integral, integration, measure (mathematics), measure, infinite sequences, series ( ...

. He was President of the

Moscow Mathematical Society The Moscow Mathematical Society (MMS) is a society of Moscow mathematicians aimed at the development of mathematics in Russia. It was created in 1864, and Victor Vassiliev is the current president. History The first meeting of the society w ...

(1923–1930).

Life

Egorov held spiritual beliefs to be of great importance, and openly defended the Church against Marxist supporters after the

Russian Revolution The Russian Revolution was a period of Political revolution (Trotskyism), political and social revolution, social change in Russian Empire, Russia, starting in 1917. This period saw Russia Dissolution of the Russian Empire, abolish its mona ...

. He was elected president of the

in 1921, and became director of the Institute for Mechanics and Mathematics at

Moscow State University Moscow State University (MSU), officially M. V. Lomonosov Moscow State University,. is a public university, public research university in Moscow, Russia. The university includes 15 research institutes, 43 faculties, more than 300 departments, a ...

in 1923. He also edited the journal ''

Matematicheskii Sbornik ''Matematicheskii Sbornik'' (, abbreviated ''Mat. Sb.'') is a peer reviewed Russian mathematical journal founded by the Moscow Mathematical Society in 1866. It is the oldest successful Russian mathematical journal. The English translation is ''Sbor ...

'' of the Moscow Mathematical Society. However, because of Egorov's stance against the repression of the

Russian Orthodox Church The Russian Orthodox Church (ROC; ;), also officially known as the Moscow Patriarchate (), is an autocephaly, autocephalous Eastern Orthodox Church, Eastern Orthodox Christian church. It has 194 dioceses inside Russia. The Primate (bishop), p ...

, he was dismissed from the Institute in 1929 and publicly rebuked. In 1930 he was arrested and imprisoned as a "religious sectarian", and soon after was expelled from the

. Upon imprisonment, Egorov began a

hunger strike A hunger strike is a method of non-violent resistance where participants fasting, fast as an act of political protest, usually with the objective of achieving a specific goal, such as a policy change. Hunger strikers that do not take fluids are ...

until he was taken to the prison hospital, and eventually to the house of fellow mathematician Nikolai Chebotaryov where he died. He was buried in Arskoe Cemetery in

Kazan Kazan; , IPA: Help:IPA/Tatar, ɑzanis the largest city and capital city, capital of Tatarstan, Russia. The city lies at the confluence of the Volga and the Kazanka (river), Kazanka Rivers, covering an area of , with a population of over 1. ...

Research work

Egorov studied

potential Potential generally refers to a currently unrealized ability. The term is used in a wide variety of fields, from physics to the social sciences to indicate things that are in a state where they are able to change in ways ranging from the simple r ...

surfaces and triply

orthogonal In mathematics, orthogonality (mathematics), orthogonality is the generalization of the geometric notion of ''perpendicularity''. Although many authors use the two terms ''perpendicular'' and ''orthogonal'' interchangeably, the term ''perpendic ...

systems, and made contributions to the broader areas of

and

integral equation In mathematical analysis, integral equations are equations in which an unknown function appears under an integral sign. In mathematical notation, integral equations may thus be expressed as being of the form: f(x_1,x_2,x_3,\ldots,x_n ; u(x_1,x_2 ...

s. His work was influenced by that of

Jean Gaston Darboux Jean-Gaston Darboux FAS MIF FRS FRSE (14 August 1842 – 23 February 1917) was a French mathematician. Life According to his birth certificate, he was born in Nîmes in France on 14 August 1842, at 1 am. However, probably due to the midn ...

on differential geometry and by

Henri Lebesgue Henri Léon Lebesgue (; ; June 28, 1875 – July 26, 1941) was a French mathematician known for his Lebesgue integration, theory of integration, which was a generalization of the 17th-century concept of integration—summing the area between an ...

. A theorem in

real analysis In mathematics, the branch of real analysis studies the behavior of real numbers, sequences and series of real numbers, and real functions. Some particular properties of real-valued sequences and functions that real analysis studies include co ...

and

integration theory Integration may refer to: Biology *Multisensory integration *Path integration * Pre-integration complex, viral genetic material used to insert a viral genome into a host genome *DNA integration, by means of site-specific recombinase technology, ...

, Egorov's Theorem, is named after him.He published a proof of this theorem in the short paper , and the result become widely acknowledged under his name. Carlo Severini had published a proof of the same result a year before, in the paper ; however, the work of Severini was unnoticed until

Leonida Tonelli Leonida Tonelli (19 April 1885 – 12 March 1946) was an Italian people, Italian mathematician, noted for proving Fubini's theorem#Tonelli's theorem for non-negative measurable functions, Tonelli's theorem, a variation of Fubini's theorem, and f ...

recalled attention on it (see the entry about Carlo Severini for further details).

Works

*, available at Gallica.

Notes

Bibliography

*. *.

External links

* {{DEFAULTSORT:Egorov, Dimitri Mathematicians from the Russian Empire Differential geometers Academic staff of Moscow State University Corresponding Members of the Russian Academy of Sciences (1917–1925) Corresponding Members of the USSR Academy of Sciences Honorary members of the USSR Academy of Sciences Mathematicians from Moscow Egorov, Dmitri 1869 births 1931 deaths Academic staff of Imperial Moscow University Imperial Moscow University alumni Burials at Arskoe Cemetery Russian scientists Victims of anti-religious campaign in the Soviet Union