# Banach, Stefan (1892–1945)

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.