Werner Fenchel

Moritz Werner Fenchel ( May 3, 1905 in Berlin, † January 24, 1988 in Copenhagen) was a Danish mathematician with German roots.

Fennel was the son of a merchant and studied from 1923 Mathematics and Physics ( with Erwin Schrödinger ) at the Humboldt University of Berlin, where he received his doctorate in 1928 at Ludwig Bieberbach (over curvature and torsion of closed space curves, Mathematische Annalen Bd.101, 1929, S .238 ). From 1928 to 1933 he was assistant to Edmund Landau at the University of Göttingen. In 1930, he worked as a Rockefeller Fellow guest stays in Copenhagen with Harald Bohr and Tommy BONNESEN and in Rome by Tullio Levi -Civita. In 1933 he fled as a Jew from the Nazis to Denmark, where he fought with translations and as an editor of the Zentralblatt für Mathematik and research associate at the Mathematical Seminar of the University of Copenhagen was before he taught at the Technical University in Copenhagen in 1938. From 1942 he was a lecturer in mathematics at the University of Copenhagen. In 1943 he fled to Sweden, where he taught until 1945 in Lund in the Danish school. From 1947 he was a lecturer at the Technical University in Copenhagen. From 1949 to 1951 he was in the U.S. at the University of Southern California, Stanford University and Princeton University. From 1952 he was professor of mechanics at the Technical University in Copenhagen and from 1956 professor at the University of Copenhagen. In 1974 he retired.

Fennel employed, inter alia, to with differential geometry, geometry of numbers and theory of convexity, and later with the discontinuous groups of motions in the Euclidean plane. With Jakob Nielsen, he is named for the Fenchel- Nielsen coordinates on Teichmüller space.

In 1946 he was admitted to the Royal Danish Academy of Sciences. He published the collected works of Jakob Nielsen.

He was married since 1933 with Kate Sperling ( 1905-1983 ), also a mathematician and Jewish woman who fled from Germany and the circumstances of the times could not graduate accordingly. She was in Berlin in 1928 her teacher's exam in mathematics, was at times a math teacher, published several papers on group theory and taught in the late 1960s in part-time at Aarhus University.

To fennel students Peter Scherk heard.

Writings

• With T. BONNESEN: Theory of convex bodies. Results in mathematics, Springer -Verlag, 1934, 1974.
• With T. BONNESEN: Elementary Geometry in hyperbolic space. de Gruyter 1989.
• Memories from the period of study. In: Yearbook surveys mathematics. BI Publisher 1980.
• Convexity through the ages. In: Gruber, Wills (Editor): Convexity and its applications. Birkhäuser 1983.