# Klaus Wagner (mathematician)

**Klaus Wagner** (born March 31, 1910 in Cologne- Klettenberg; † February 6, 2000 ) was a German mathematician . He is considered to be one of the pioneers of graph theory .

## Life and career

Klaus Wagner was the youngest of four sons of the accountant and authorized signatory Christian Wagner. He attended the Realgymnasium in Cologne-Lindenthal and graduated from high school there in 1930 . He then studied mathematics , physics , chemistry and meteorology at the University of Cologne . Wagner was in 1934 Karl Dörge with the work *over two sets of the topology: Jordan Curve Theorem and four color problem *doctorate . As a post-doctoral student he was with Kurt Reidemeister at the University of Marburg .

After completing his studies, Wagner worked as a meteorologist at Cologne and Berlin airports and was also active in this function during the Second World War .

Wagner returned to mathematics after the end of the war and completed his habilitation in 1949 at the University of Cologne with the text *Topological Treatment of the Fundamentals in Infinitesimal Calculus* . There he became a scientific advisor and professor in 1956 . In 1970 he received a call to the University of Duisburg , whereupon the University of Cologne appointed him honorary professor in 1971 . In 1978 he retired .

Wagner lived in Cologne-Rath, had been married to Hanna Wagner since 1950 and had a son and a daughter.

His doctoral students include Rudolf Halin , Bruno Bosbach (Kassel), Heinz Jung (TU Berlin) and Egbert Harzheim .

## Scientific achievements

Klaus Wagner made significant achievements in pure mathematics , not least in topology and graph theory, and in particular in the field of topological graph theory . Be highlighted results as the equivalent set of Wagner , the set of Wagner and the set of Wagner and Fary . The *Wagner graph is* named after *Wagner* . Likewise, the Wagnerian Hypothesis goes back to him , the proof of which was provided in 2004 by Neil Robertson and Paul Seymour , which is known as the Robertson-Seymour Theorem . It is a reformulation of Kuratowski's theorem by replacing topological minors (Kuratowski) with graph minors and was first formulated by Wagner in 1937.

## Honors

In 1985, in honor of Klaus Wagner, the commemorative publication *Graphs in Research and Education* was published. In 1997, Wagner received an honorary doctorate from the University of Duisburg . In June 2000, a celebratory colloquium was held posthumously in his memory at the University of Cologne .

## Fonts

Klaus Wagner was the author or co-author of 62 scientific publications and 7 specialist books , not least the following much-cited textbook:

- Klaus Wagner: Theory of graphs (= BI university pocket books. 248 / 248a). Bibliographisches Institut, Mannheim (inter alia) 1970, ISBN 3-411-00248-4 .

## Festschrift

- Rainer Bodendiek , Heinz Schumacher , Gerd Walther (eds.): Graphs in research and teaching . Festschrift K. Wagner. Verlag Barbara Franzbecker , Bad Salzdetfurth / Hildesheim 1985, ISBN 3-88120-086-X .

## literature

- Rainer Bodendiek, Bruno Bosbach: Klaus Wagner (1910-2000) . In: Results in Mathematics . tape 41 , 2002, p. 3-17 ( link.springer.com ). MR1888715

## Web links

- Literature by and about Klaus Wagner in the catalog of the German National Library
- Graph Theory Families page also on Klaus Wagner (Columbia University)
- Entry in: The Mathematics Genealogy Project

## Individual evidence

- ↑ Klaus Wagner in the Mathematics Genealogy Project (English)
- ^ Wagner, On an expansion of Kuratowski's theorem, Deutsche Mathematik, Volume 2, 1937, pp. 280–285
- ^ Bill Casselman, Variations on Graph Minor, AMS

personal data | |
---|---|

SURNAME | Wagner, Klaus |

BRIEF DESCRIPTION | German mathematician and university professor |

DATE OF BIRTH | March 31, 1910 |

PLACE OF BIRTH | Cologne |

DATE OF DEATH | February 6, 2000 |