# Helmut Hasse

**Helmut Hasse** (German: [ˈhasə]; 25 August 1898 – 26 December 1979) was a German mathematician^{[1]} working in algebraic number theory, known for fundamental contributions to class field theory, the application of *p*-adic numbers to local class field theory and diophantine geometry (Hasse principle), and to local zeta functions.

Hasse was born in Kassel, Province of Hesse-Nassau,^{[2]} the son of Judge Paul Reinhard Hasse, also written Haße (12 April 1868 – 1 June 1940,^{[3]} son of Friedrich Ernst Hasse and his wife Anna Von Reinhard) and his wife Margarethe Louise Adolphine Quentin (born 5 July 1872 in Milwaukee, daughter of retail toy merchant^{[4]} Adolph Quentin (b. May 1832, probably Berlin, Kingdom of Prussia) and Margarethe Wehr (b. about 1840, Prussia),^{[5]} then raised in Kassel).^{[6]}

After serving in the Imperial German Navy in World War I, he studied at the University of Göttingen, and then at the University of Marburg under Kurt Hensel, writing a dissertation in 1921 containing the Hasse–Minkowski theorem, as it is now called, on quadratic forms over number fields. He then held positions at Kiel, Halle and Marburg. He was Hermann Weyl's replacement at Göttingen in 1934.

Hasse was an Invited Speaker of the International Congress of Mathematicians (ICM) in 1932 in Zürich and a Plenary Speaker of the ICM in 1936 in Oslo.^{[7]}

Politically, he applied for membership in the Nazi Party in 1937, but this was denied to him allegedly due to his remote Jewish ancestry.^{[8]} After the war, he briefly returned to Göttingen in 1945, but was excluded by the British authorities. After brief appointments in Berlin, from 1948 on he settled permanently as professor in Hamburg.

He collaborated with many mathematicians, in particular with Emmy Noether and Richard Brauer on simple algebras, and with Harold Davenport on Gauss sums (Hasse–Davenport relations), and with Cahit Arf on the Hasse–Arf theorem.