Hans Hahn

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Hans Hahn (born September 27, 1879 in Vienna , † July 24, 1934 in Vienna) was an Austrian mathematician and philosopher, best known for Hahn-Banach's theorem.


Hahn began his academic career in 1898 when he began studying law at the University of Vienna. After a year he turned to mathematics and studied in Strasbourg and Munich. In 1901 Hahn returned to Vienna, where in 1902 he completed his doctorate on the subject of "On the theory of the second variation of simple integrals" and thus received a Dr. phil. was appointed. During his time at the Technical University in Vienna, he became friends with Paul Ehrenfest , Heinrich Tietze and Gustav Herglotz . In 1905 he completed his habilitation at the University of Vienna with the thesis “Comments on the calculus of variations” . He taught in Czernowitz , Bonn and from 1921 as a full university professor at the University of Vienna . Also in 1921 he was elected a member of the Leopoldina . His most famous student was Kurt Gödel , who completed his doctoral thesis in 1929.

Hahn was also very interested in philosophy and an active member of the Vienna Circle . Hahn was involved in university politics as chairman of the Association of Socialist University Lecturers and in local politics as a member of the Vienna City School Council . He protested against the discrimination against Jewish students and professors and was the target of an anti-Semitic defamation campaign by the Deutschösterreichische Tages-Zeitung in 1924. Hahn demanded unrestricted freedom of teaching and learning, free tuition and a habilitation process based exclusively on academic achievement.

In 1934 he died of an operation at the age of 54.

In 1921 he received the Richard Lieben Prize . In 1926 he was President of the German Mathematicians Association .


The name Hans Hahn is best known from Hahn-Banach's sentence . In addition, Hahn made other important contributions to functional analysis , to measure theory ( Hahn's decomposition theorem , theorem of Vitali-Hahn-Saks ), to harmonic analysis and to general topology . The majority of Hahn's publications are the above-mentioned writings of mathematical content. Hans Hahn did not publish texts with a philosophical content until the early 1930s. These deal with epistemological considerations for the natural sciences.

PhD students

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