Gerhard Ringel

Gerhard Ringel (October 28, 1919, in Kollnbrunn, Austria - June 24, 2008, in Santa Cruz, California) was a German mathematician who earned his Ph.D. from the University of Bonn in 1951. He was one of the pioneers in graph theory and contributed significantly to the proof of the Heawood conjecture (now Ringel-Youngs theorem), a mathematical problem closely linked with the Four color theorem.

Gerhard Ringel started his academic career as professor at the Free University Berlin. In 1970 he left Germany due to bureaucratic consequences of the German student movement, and he continued his career at the University of California, Santa Cruz. He was awarded honorary doctors degrees from the University of Karlsruhe (TH) and the Free University Berlin.

Besides his mathematical skills he was a widely acknowledged entomologist. His main emphasis lay on collecting and breeding butterflies. Prior to his death, he gave his outstanding collection of butterflies to the UCSC Museum of Natural History Collections.

Publications

• Ringel, Gerhard (1968). "Solution of the Heawood map-coloring problem". Proc. Nat. Acad. Sci. USA. 60 (2): 438–445. doi:10.1073/pnas.60.2.438. PMC 225066. PMID 16591648. MR0228378. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)
• Hartsfield, Nora (1990). Pearls in graph theory. Academic Press, Boston, MA. ISBN 0-12-328552-6. {{cite book}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)

References

Retired mathematics professor Gerhard Ringel gives his world-class butterfly collection to UCSC, UC Santa Cruz Review, Fall 2006

External links

• Gerhard Ringel at the Mathematics Genealogy Project
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