Jean Leray

{{Infobox scientist

| name = Jean Leray

| image = Jean Leray.jpeg

| image_size =

| caption = Jean Leray at Oberwolfach in 1961

| birth_date = {{birth date|1906|11|07|df=y}}

| birth_place = Chantenay-sur-Loire (today part of Nantes)

| death_date = {{death date and age|1998|11|10|1906|11|07|df=y}}

| death_place = La Baule

| field = Mathematics

| work_institutions = University of Nancy
University of Paris
Collège de France

| alma_mater = École Normale Supérieure

| doctoral_advisor = Henri Villat

| doctoral_students = Armand Borel
István Fáry

| known_for = Partial differential equations
Algebraic topology
Global hyperbolicity
Sheaf theory
Sheaf cohomology
Leray cover
Leray projection
Leray's theorem
Leray spectral sequence
Leray–Hirsch theorem
Leray–Schauder degree

| awards = Prix Francoeur {{small|(1937)}}
{{no wrap|Malaxa Prize (1938)
Feltrinelli Prize (1971)
John von Neumann Prize{{small|(1962)}}
Wolf Prize (1979)
Lomonosov Gold Medal (1988)}}

}}

Jean Leray ({{IPA|fr|ləʁɛ|lang}}; 7 November 1906 – 10 November 1998){{Cite journal | last1 = Andler | first1 = M. | doi = 10.1098/rsbm.2006.0011 | title = Jean Leray. 7 November 1906 -- 10 November 1998: Elected ForMemRS 1983 | journal = Biographical Memoirs of Fellows of the Royal Society | volume = 52 | pages = 137 | year = 2006 | doi-access = free }} was a French mathematician, who worked on both partial differential equations and algebraic topology.

Life and career

He was born in Chantenay-sur-Loire (today part of Nantes). He studied at École Normale Supérieure from 1926 to 1929. He received his Ph.D. in 1933. In 1934 Leray published an important paper that founded the study of weak solutions of the Navier–Stokes equations.{{cite journal|year=1934|title=Sur le mouvement d'un liquide visqueux emplissant l'espace|url=http://www.math.cornell.edu/~bterrell/leray.pdf|journal=Acta Mathematica|volume=63|pages=193–248|doi=10.1007/BF02547354|last=Leray|first= Jean|s2cid=121452337|doi-access=free}} In the same year, he and Juliusz Schauder discovered{{cite journal|last1=Leray|first1=Jean|last2=Schauder|first2=Juliusz|author-link=Juliusz Schauder|title=Topologie et équations fonctionelles|journal=Annales Scientifiques de l'École Normale Supérieure|year=1934|volume=51|pages=45–78| zbl=0009.07301 | jfm=60.0322.02|doi=10.24033/asens.836|doi-access=free}} 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. He did not join the Bourbaki group, although he was close with its founders.

His main work in topology was carried out while he was a prisoner of war in a camp in Edelbach, Austria from 1940 to 1945. He concealed his expertise on differential equations, fearing that its connections with applied mathematics could lead him to be asked to do war work.

Leray's work of this period proved seminal to the development of spectral sequences and sheaves.{{cite book | last = Dieudonné | first = Jean | author-link = Jean Dieudonné | title = A history of algebraic and differential topology 1900–1960 | publisher = Birkhäuser | year = 1989 | pages = [https://archive.org/details/historyofalgebra0000dieu_g9a3/page/123 123–141] | isbn = 0-8176-3388-X | url = https://archive.org/details/historyofalgebra0000dieu_g9a3/page/123 }} These were subsequently developed by many others,{{cite web | last = Miller | first = Haynes |author-link=Haynes Miller | title = Leray in Oflag XVIIA: The origins of sheaf theory, sheaf cohomology, and spectral sequences | year = 2000 | url = http://www-math.mit.edu/~hrm/papers/ss.pdf }} each separately becoming an important tool in homological algebra.

He returned to work on partial differential equations from about 1950.

He was professor at the University of Paris from 1945 to 1947, and then at the Collège de France until 1978.

He was awarded the Malaxa Prize (Romania, 1938), the Grand Prix in mathematical sciences (French Academy of Sciences, 1940), the Feltrinelli Prize (Accademia dei Lincei, 1971), the Wolf Prize in Mathematics (Israel, 1979), and the Lomonosov Gold Medal (Moscow, 1988). He was an elected to the American Academy of Arts and Sciences and the American Philosophical Society in 1959 and the United States National Academy of Sciences in 1965.{{Cite web |title=Jean Leray |url=https://www.amacad.org/person/jean-leray |access-date=2022-12-06 |website=American Academy of Arts & Sciences |language=en}}{{Cite web |title=APS Member History |url=https://search.amphilsoc.org/memhist/search?creator=Jean+Leray&title=&subject=&subdiv=&mem=&year=&year-max=&dead=&keyword=&smode=advanced |access-date=2022-12-06 |website=search.amphilsoc.org}}

References

External links

{{MacTutor Biography|id=Leray}}
{{MathGenealogy |id=38471}}
[https://www.ams.org/notices/200003/mem-leray.pdf "Jean Leray (1906–1998)"], by Armand Borel, Gennadi M. Henkin, and Peter D. Lax, Notices of the American Mathematical Society, vol. 47, no. 3, March 2000.
[https://web.archive.org/web/20070927044951/http://www.impan.gov.pl/~leray/leraydefault.html Jean Leray] Short biography