Ernst Sigismund Fischer

Ernst Sigismund Fischer ( born July 12, 1875 in Vienna, † November 14, 1954 in Cologne) was an Austrian mathematician who worked on analysis and algebra.

Life and work

Ernst Sigismund Fischer was the son of the composer and music professor Jacob Fischer and studied from 1894 in Vienna ( and a semester in Berlin ) and others Franz Mertens. In 1899, he was there his doctorate under Leopold Gegenbauer. Then he was still studying at Hermann Minkowski in Zurich and Göttingen. In 1902, he was assistant to E. Waelsch at the German Technical University in Brno. In 1904 he was a lecturer there in 1910 and associate professor. In 1911 he was a professor in Erlangen as the successor of Paul Gordan, adjacent to Emmy Noether at the Mathematics Department, was on which he exercised in the words of Hermann Weyl greater influence than her doctor father Gordan, since in contrast to this a more abstract point of view it in the algebra in the sense of the school of David Hilbert represented. After military service in World War I, he was from 1920 professor in Cologne, where he was forced into retirement because of Jewish ancestors in 1938.

Fishing is mainly for his proof of the Riesz Frigyes named after him and set of Fischer- Riesz known about the completeness of the space quadratintegrabler functions. In its corresponding work of 1907, he also led the " convergence in the mean " in the. With simultaneous work of Frigyes Riesz ( 1907), which was an important step towards the development of the Hilbert space. They used the Lebesgue integral, and their set was one of the early successes of the theory of integration by Henri Lebesgue.

In 1931 he was president of the German Mathematical Society.

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