Who developed one of the foundations of functional analysis and also taught Hugo Steinhaus?
Hugo Steinhaus Władysław Hugo Dionizy Steinhaus (January 14, 1887 – February 25, 1972) was a Polish mathematician and educator. Steinhaus obtained his PhD under David Hilbert at Göttingen University in 1911 and later became a professor at the Jan Kazimierz University in Lwów (now Lviv, Ukraine), where he helped establish what later became known as the Lwów School of Mathematics. He is credited with "discovering" mathematician Stefan Banach, with whom he gave a notable contribution to functional analysis through the Banach–Steinhaus theorem. After World War II Steinhaus played an important part in the establishment of the mathematics department at Wrocław University and in the revival of Polish mathematics from the destruction of the war.
Julius Ebbinghaus Julius Ebbinghaus (9 November 1885, Berlin – 16 June 1981, Marburg an der Lahn) was a German philosopher, one of the closest followers of Immanuel Kant active in the twentieth century. He was influenced by the Heidelberg school of neo-Kantianism of Wilhelm Windelband, and wrote on philosophy of law and the categorical imperative. Professor at Marburg University (Philipps-Universität Marburg) since 1940; 1954 professor emeritus, continuing lectures until 1966. In October 1945, he became installed as Rector Magnificus by order of the American occupation forces. He was the son of famous psychologist Hermann Ebbinghaus.