Banach, Stefan (1892–1945)

Stefan Banach

Stefan Banach was a great Polish mathematician who founded functional analysis and also made important contributions to the understanding of vector spaces, measure theory, and set theory. His name is associated with Banach space, Banach algebra, the Hahn-Banach Theorem, and the remarkable Banach-Tarski paradox.


Largely self-taught in mathematics, Banach was "discovered" by Hugo Steinhaus and when World War II began was President of the Polish Mathematical Society and a full professor at Lvov University. Being on good terms with Soviet mathematicians, he was allowed to hold his chair during the Soviet occupation of Lvov. The German occupation of the city in 1941 resulted in the mass murder of Polish academics. Banach survived, but the only way he could work for a living was by feeding lice with his blood in a German institute where typhoid fever research was conducted. His health undercut during the occupation, Banach died before he could be repatriated from Lvov, which was incorporated into the Soviet Union, to Poland after the war. Théorie des opérations linéaires (Teoria operacji liniowych, 1932) is regarded as his most influential work.