Stefan Banach

Name	Stefan Banach
Birth date	March 30, 1892
Birth place	Kraków, Grand Duchy of Cracow, Austria-Hungary
Death date	August 31, 1945
Death place	Lviv, Ukraine, Soviet Union
Nationality	Polish
Citizenship	Austro-Hungarian, Polish, Soviet Union
Field	mathematics
Work institutions	Lviv University
Alma mater	Lviv Polytechnic
Doctoral advisor	Hugo Steinhaus
Doctoral students	Stanisław MazurStanisław Ulam
Known for	Banach–Tarski paradoxBanach–Steinhaus theoremFunctional analysis
Prizes	Memberships:Academy of Sciences of the Ukrainian SSR,Polish Academy of Learning

Stefan Banach (; March 30, 1892 – August 31, 1945) was a Polish mathematician who worked in interwar Poland and in Soviet Ukraine. He is generally considered to have been one of the 20th century's most important and influential mathematicians.

A self-taught mathematics prodigy, Banach was the founder of modern functional analysis and a founder of the Lwów School of Mathematics. Among his most prominent achievements was the 1932 book, Théorie des opérations linéaires (Theory of Linear Operations), the first monograph on the general theory of functional analysis.

Notable mathematical concepts named after Banach include the Banach–Tarski paradox, the Hahn–Banach theorem, the Banach–Steinhaus theorem, the Banach-Mazur game, and the Banach space.

Early life

Stefan Banach was born on 30 March 1892 at St. Lazarus General Hospital in Kraków, then part of Austro-Hungarian Galicia. Banach's parents were Stefan Greczek and one Katarzyna Banach, both natives of the Podhale region. Stefan Greczek was born in Ostrowsko near the town of Nowy Targ and at one time was a soldier in the Austro-Hungarian Army stationed in Kraków. Stefan Greczek's father, Józef, was a farmer and a village mayor and Józef's wife, Antonina (née Borkowska) bore the Pomian coat of arms. Stefan Greczek would go on to marry twice and have a son by his first wife and four children by the second.

Unusually, Stefan's surname was that of his mother instead of his father, though he received his father's given name. Since Banach's father was a private and was prevented by military regulations from marrying, and the mother was too poor to support the child, the couple decided that he should be reared by family and friends. Family legend says that Banach spent his early childhood in Ostrowsko with his grandmother, to whom he was very close. When she became ill, his father sent him to Kraków to live with Franciszka Płowa and her daughter, Maria, although Banach would continue to visit his grandmother up to her funeral. Franciszka worked in a branch of the Tęcza laundries while her husband was the manager of the Krakowski Hotel. Together, they were able to give Banach what was a relatively comfortable life for the time. Contacts between Banach and his father were polite and cordial; though Banach loved his father, he did not show him much warmth or filial affection.

Education

As a child, Banach was introduced to Juliusz Mien, a French intellectual who had moved to Kraków in 1870 and who was a guardian of Maria Płowa. Mien guided Banach by teaching him French and supervising his education without charge. Mien likely nurtured Banach's early mathematical skills, and he taught him to speak French so fluently that later in life Banach was able to impress foreign colleagues with his knowledge of the language. however he was especially fond of Latin. After obtaining his matura at age 18 in 1910, Banach went with Witold Wiłkosz to Lviv, then the capital of Galicia, intending to enroll in engineering at the Lwów Polytechnic. However, as Banach had to earn money to support his studies, it was not until 1914 that he finally, at age 22, passed his half-diploma exams.

When World War I broke out, Banach was excused from military service due to his left-handedness and poor vision. When the Russian Army opened its offensive toward Lwów, Banach left for Kraków, to spend the rest of the war there and in other Galician towns. He made his living tutoring at local gymnasiums and working in a bookshop. He may have attended lectures at the Jagiellonian University, but little is known of that period in his life.

In 1916, in Kraków's Planty gardens, Banach encountered Professor Hugo Steinhaus, one of the renowned mathematicians of the age. Steinhaus became fascinated with the self-taught young mathematician. The encounter resulted in a long-lasting collaboration and friendship. It was also through Steinhaus that Banach met his future wife, Łucja Braus.

Work

Steinhaus introduced Banach to academic circles and substantially accelerated his career. After Poland regained independence, in 1920 Banach was given an assistantship at Kraków's Jagiellonian University. Steinhaus' backing also allowed him to receive a doctorate without actually graduating from a university. The doctoral thesis, accepted by King John II Casimir University of Lwów and published in 1922, included the basic ideas of functional analysis, which was soon to become an entirely new branch of mathematics. The thesis was widely discussed in academic circles and allowed him in 1922 to become a professor at the Lwów Polytechnic. Initially an assistant to Professor Antoni Łomnicki, in 1927 Banach received his own chair. In 1924 he was also accepted as a member of the Polish Academy of Learning. At the same time, from 1922, Banach also headed the second Chair of Mathematics at University of Lwów. Young and talented, Banach gathered around him a large group of mathematicians. The group, meeting in the Scottish Café, soon gave birth to the "Lwów School of Mathematics". In 1929 the group began publishing its own journal, Studia Mathematica, devoted primarily to Banach's field of study — functional analysis. Around that time, Banach also began working on his best-known work, the first monograph on the general theory of linear-metric space. First published in Polish in 1931, the following year it was also translated into French and gained wider recognition in European academic circles. The book was also the first in a long series of mathematics monographs edited by Banach and his circle.

Later life and death

Following the invasion of Poland by Nazi Germany and the Soviet Union, Lwów came under the control of the Soviet Union for almost two years. Banach, from 1939 a corresponding member of the Academy of Sciences of Ukraine, and on good terms with Soviet mathematicians, had to promise to learn Ukrainian to be allowed to keep his chair and continue his academic activities. Following the German takeover of Lwów in 1941 in Operation Barbarossa, all universities were closed and Banach, along with many colleagues and his son, was employed as lice feeder at Professor Rudolf Weigl's Typhus Research Institute. Employment in Weigl's Institute provided many unemployed university professors and their associates protection from random arrest and deportation to Nazi concentration camps.

After the Red Army recaptured Lviv in the Lvov–Sandomierz Offensive of 1944, Banach returned to the University and helped re-establish it after the war years. However, because the Soviets were removing Poles from annexed formerly Polish territories, Banach began preparing to leave the city and settle in Kraków, Poland, where he had been promised a chair at the Jagiellonian University. In January 1945, however, he was diagnosed with lung cancer and was allowed to stay in Lwów. He died on August 31, 1945, aged 53. His funeral at the Lychakiv Cemetery turned into a patriotic demonstration by the Poles who still remained in the city.

Works

Rachunek różniczkowy i całkowy, tom I (Differential and Integral Calculus, vol. 1), Lwów, Zakład Narodowy im. Ossolińskich, 1929, 294 pp.

Rachunek różniczkowy i całkowy, tom II (Differential and Integral Calculus, vol. 2), Lwów, Książnica-Atlas, 1930, 248 pp.

Teoria operacji. Tom l. Operacje liniowe (Theory of operations, vol. 1: Linear operations), Warsaw, Kasa im. Mianowskiego, 1931, viii + 236 pp.

Théorie des opérations linéaires, Monografie Matematyczne 1 (Theory of Linear Operations, Mathematical Monographs 1), Warsaw, 1932, vii + 254 pp.

Mechanika w zakresie szkół akademickich, Monografie Matematyczne 8 (Mechanics for Academic Schools, Mathematical Monographs 8), Warsaw, Lwów, Wilno, 1938.

Banach's most influential work was Théorie des opérations linéaires (Theory of Linear Operations, 1932). In it he formulated the concept now known as "Banach space", and proved many fundamental theorems of functional analysis.

Besides being one of the founders of functional analysis, Banach also made important contributions to measure theory, set theory, and other branches of mathematics.

He was also one of the founders and editors of the journal, Studia Mathematica.

Quotes

Stanisław Ulam, another mathematician of the Lwów School of Mathematics, in his autobiography, quotes Banach as saying: : "Good mathematicians see analogies. Great mathematicians see analogies between analogies."

Hugo Steinhaus said of Banach: : "An exceptional intellect, exceptional discoveries... he gave Polish science... more than anybody else." : "Banach was my greatest scientific discovery."

See also

16856 Banach

Amenable Banach algebra

Banach–Alaoglu theorem

Banach algebra

Banach bundle

Banach fixed point theorem

Banach function algebra

Banach integral

Banach limit

Banach manifold

Banach's matchbox problem

Banach measure

Banach space

Banach–Mazur game

Banach–Mazur theorem

Banach–Schauder theorem

Banach–Stone theorem

Banach–Tarski paradox

Closed range theorem

Functional analysis

Legitimacy

List of Poles

Notes

References

External links

Page devoted to Stefan Banach

Théorie des opérations linéaires French translation from 1932

The MacTutor History of Mathematics archive Article on Stefan Banach

Category:1892 births Category:1945 deaths Category:20th-century mathematicians Category:20th-century Austrian people Category:20th-century Polish people Category:Soviet people Category:20th-century Ukrainian people Category:Polish mathematicians Category:Austrian mathematicians Category:Soviet mathematicians Category:Ukrainian mathematicians Category:Members of the Lwów Scientific Society Category:Members of the Polish Academy of Learning Category:Members of the National Academy of Sciences of Ukraine Category:Alumni of Lviv Polytechnic Category:Polish Gorals Category:Polish Austro-Hungarians Category:Polish expatriates in the Soviet Union Category:Polish expatriates in Ukraine Category:People from Kraków Category:People from Lviv