# Stephan Cohn-Vossen

**Stefan** or **Stephan Cohn-Vossen** (28 May 1902 – 25 June 1936) was a mathematician, who was responsible for Cohn-Vossen's inequality and the Cohn-Vossen transformation is also named for him.[1] He proved the first version of Splitting theorem.

Stephan Cohn-Vossen | |
---|---|

in Moscow, probably 1936 | |

Born | |

Died | June 25, 1936 34) | (aged

Cause of death | Pneumonia |

Alma mater | Wrocław University |

Known for | Cohn-Vossen's inequality |

Scientific career | |

Thesis | Singuläre Punkte reeller, schlichter Kurvenscharen, deren Differentialgleichung gegeben ist (1924) |

Doctoral advisor | Adolf Kneser |

He was also known for his collaboration with David Hilbert on the 1932 book *Anschauliche Geometrie*, translated into English as *Geometry and the Imagination*.[2]

He was born in Breslau (then a city in the Kingdom of Prussia; now Wrocław in Poland). He wrote a 1924 doctoral dissertation at the University of Breslau (now the University of Wrocław) under the supervision of Adolf Kneser.[3] He became a professor at the University of Cologne in 1930.

He was barred from lecturing in 1933 under Nazi racial legislation, because he was Jewish.[4] In 1934 he emigrated to the USSR, with some help from Herman Müntz.[5] While there, he taught at Leningrad University. He died in Moscow from pneumonia.[6]

## See also

## References

- Voitsekhovskii, M.I. (2001) [1994], "Cohn-Vossen transformation", in Hazewinkel, Michiel (ed.),
*Encyclopedia of Mathematics*, Springer Science+Business Media B.V. / Kluwer Academic Publishers, ISBN 978-1-55608-010-4 - Hilbert, David; Cohn-Vossen, Stephan (1952).
*Geometry and the Imagination*(2nd ed.). Chelsea. ISBN 0-8284-1087-9. - Stephan Cohn-Vossen at the Mathematics Genealogy Project
- Siegmund-Schultze, Reinhard (2009),
*Mathematicians Fleeing from Nazi Germany: Individual Fates and Global Impact*, Princeton University Press, pp. 132, 133, 346, 370, 373, 399, ISBN 9780691140414. - Siegmund-Schultze 2009 (p.133) quotes from a 1937 letter by Müntz: "The appointments of Cohn-Vossen, Walfisz, Pollaczek (the latter was not allowed to slip in again) were immediately influenced by myself, the ones for Plessner and Bergmann indirectly."
- Cohn-Vossen's Obituary (in Russian)

## External links

- Anschauliche Geometrie at Göttinger Digitalisierungszentrum
- Cohn-Vossen transformation at Encyclopedia of Mathematics