Jean Leray (; 7 November 1906 – 10 November 1998) was a French

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 ...

, who worked on both

partial differential equation In mathematics, a partial differential equation (PDE) is an equation which involves a multivariable function and one or more of its partial derivatives. The function is often thought of as an "unknown" that solves the equation, similar to ho ...

s and

algebraic topology Algebraic topology is a branch of mathematics that uses tools from abstract algebra to study topological spaces. The basic goal is to find algebraic invariant (mathematics), invariants that classification theorem, classify topological spaces up t ...

Life and career

He was born in Chantenay-sur-Loire (today part of

Nantes Nantes (, ; ; or ; ) is a city in the Loire-Atlantique department of France on the Loire, from the Atlantic Ocean, Atlantic coast. The city is the List of communes in France with over 20,000 inhabitants, sixth largest in France, with a pop ...

). He studied at

École Normale Supérieure École or Ecole may refer to: * an elementary school in the French educational stages normally followed by Secondary education in France, secondary education establishments (collège and lycée) * École (river), a tributary of the Seine flowing i ...

from 1926 to 1929. He received his Ph.D. in 1933. In 1934 Leray published an important paper that founded the study of

weak solution In mathematics, a weak solution (also called a generalized solution) to an ordinary or partial differential equation is a function for which the derivatives may not all exist but which is nonetheless deemed to satisfy the equation in some prec ...

s of the

Navier–Stokes equations The Navier–Stokes equations ( ) are partial differential equations which describe the motion of viscous fluid substances. They were named after French engineer and physicist Claude-Louis Navier and the Irish physicist and mathematician Georg ...

. In the same year, he and

Juliusz Schauder Juliusz Paweł Schauder (; 21 September 1899 – September 1943) was a Polish mathematician known for his work in functional analysis, partial differential equations and mathematical physics. Life and career Born on 21 September 1899 in Lwów ...

discovered a topological invariant, now called the Leray–Schauder degree, which they applied to prove the existence of solutions for partial differential equations lacking uniqueness. From 1938 to 1939 he was professor at the

University of Nancy A university () is an institution of tertiary education and research which awards academic degrees in several academic disciplines. ''University'' is derived from the Latin phrase , which roughly means "community of teachers and scholars". Uni ...

. He did not join the

Bourbaki group Bourbaki(s) may refer to : Persons and science * Charles-Denis Bourbaki (1816–1897), French general, son of Constantin Denis Bourbaki * Colonel Constantin Denis Bourbaki (1787–1827), officer in the Greek War of Independence and serving in t ...

, although he was close with its founders. His main work in

topology Topology (from the Greek language, Greek words , and ) is the branch of mathematics concerned with the properties of a Mathematical object, geometric object that are preserved under Continuous function, continuous Deformation theory, deformat ...

was carried out while he was a

prisoner of war A prisoner of war (POW) is a person held captive by a belligerent power during or immediately after an armed conflict. The earliest recorded usage of the phrase "prisoner of war" dates back to 1610. Belligerents hold prisoners of war for a ...

in a camp in Edelbach, Austria from 1940 to 1945. He concealed his expertise on differential equations, fearing that its connections with

applied mathematics Applied mathematics is the application of mathematics, mathematical methods by different fields such as physics, engineering, medicine, biology, finance, business, computer science, and Industrial sector, industry. Thus, applied mathematics is a ...

could lead him to be asked to do war work. Leray's work of this period proved seminal to the development of

spectral sequence In homological algebra and algebraic topology, a spectral sequence is a means of computing homology groups by taking successive approximations. Spectral sequences are a generalization of exact sequences, and since their introduction by , they h ...

s and sheaves. These were subsequently developed by many others, each separately becoming an important tool in

homological algebra Homological algebra is the branch of mathematics that studies homology (mathematics), homology in a general algebraic setting. It is a relatively young discipline, whose origins can be traced to investigations in combinatorial topology (a precurs ...

. He returned to work on partial differential equations from about 1950. He was professor at the

University of Paris The University of Paris (), known Metonymy, metonymically as the Sorbonne (), was the leading university in Paris, France, from 1150 to 1970, except for 1793–1806 during the French Revolution. Emerging around 1150 as a corporation associated wit ...

from 1945 to 1947, and then at the

Collège de France The (), formerly known as the or as the ''Collège impérial'' founded in 1530 by François I, is a higher education and research establishment () in France. It is located in Paris near La Sorbonne. The has been considered to be France's most ...

until 1978. He was awarded the Malaxa Prize (

Romania Romania is a country located at the crossroads of Central Europe, Central, Eastern Europe, Eastern and Southeast Europe. It borders Ukraine to the north and east, Hungary to the west, Serbia to the southwest, Bulgaria to the south, Moldova to ...

, 1938), the Grand Prix in mathematical sciences (

French Academy of Sciences The French Academy of Sciences (, ) is a learned society, founded in 1666 by Louis XIV at the suggestion of Jean-Baptiste Colbert, to encourage and protect the spirit of French Scientific method, scientific research. It was at the forefron ...

, 1940), the

Feltrinelli Prize The Feltrinelli Prize (from the Italian "Premio Feltrinelli", also known as "International Feltrinelli Prize" or "Antonio Feltrinelli Prize") is an award for achievement in the arts, music, literature, history, philosophy, medicine, and physical a ...

(

Accademia dei Lincei The (; literally the "Academy of the Lynx-Eyed"), anglicised as the Lincean Academy, is one of the oldest and most prestigious European scientific institutions, located at the Palazzo Corsini on the Via della Lungara in Rome, Italy. Founded in ...

, 1971), the

Wolf Prize in Mathematics The Wolf Prize in Mathematics is awarded almost annually by the Wolf Foundation in Israel. It is one of the six Wolf Prizes established by the Foundation and awarded since 1978; the others are in Agriculture, Chemistry, Medicine, Physics and Arts. ...

(

Israel Israel, officially the State of Israel, is a country in West Asia. It Borders of Israel, shares borders with Lebanon to the north, Syria to the north-east, Jordan to the east, Egypt to the south-west, and the Mediterranean Sea to the west. Isr ...

, 1979), and the

Lomonosov Gold Medal The Lomonosov Gold Medal ( ''Bol'shaya zolotaya medal' imeni M. V. Lomonosova''), named after Russian scientist and polymath Mikhail Lomonosov, is awarded each year since 1959 for outstanding achievements in the natural sciences and the humaniti ...

(

Moscow Moscow is the Capital city, capital and List of cities and towns in Russia by population, largest city of Russia, standing on the Moskva (river), Moskva River in Central Russia. It has a population estimated at over 13 million residents with ...

, 1988). He was an elected to the

American Academy of Arts and Sciences The American Academy of Arts and Sciences (The Academy) is one of the oldest learned societies in the United States. It was founded in 1780 during the American Revolution by John Adams, John Hancock, James Bowdoin, Andrew Oliver, and other ...

and the

American Philosophical Society The American Philosophical Society (APS) is an American scholarly organization and learned society founded in 1743 in Philadelphia that promotes knowledge in the humanities and natural sciences through research, professional meetings, publicat ...

in 1959 and the United States

National Academy of Sciences The National Academy of Sciences (NAS) is a United States nonprofit, NGO, non-governmental organization. NAS is part of the National Academies of Sciences, Engineering, and Medicine, along with the National Academy of Engineering (NAE) and the ...

in 1965.

References

External links

* *
"Jean Leray (1906–1998)"
by

Armand Borel Armand Borel (21 May 1923 – 11 August 2003) was a Swiss mathematician, born in La Chaux-de-Fonds, and was a permanent professor at the Institute for Advanced Study in Princeton, New Jersey, United States from 1957 to 1993. He worked in alg ...

, Gennadi M. Henkin, and Peter D. Lax, ''Notices of the American Mathematical Society'', vol. 47, no. 3, March 2000.
''Jean Leray''
Short biography {{DEFAULTSORT:Leray, Jean 1906 births 1998 deaths 20th-century French mathematicians French mathematical analysts Topologists École Normale Supérieure alumni Wolf Prize in Mathematics laureates Members of the French Academy of Sciences Foreign members of the Royal Society Foreign members of the USSR Academy of Sciences Foreign members of the Russian Academy of Sciences Foreign associates of the National Academy of Sciences Institute for Advanced Study visiting scholars Partial differential equation theorists Academic staff of Nancy-Université French prisoners of war in World War II Members of the American Philosophical Society

Life and career

See also

References

External links