Gerhard Ringel

Gerhard Ringel (October 28, 1919 in Kollnbrunn, Austria – June 24, 2008 in Santa Cruz, California) was a German mathematician. He was one of the pioneers in graph theory and contributed significantly to the proof of the Heawood conjecture (now the Ringel-Youngs theorem), a mathematical problem closely linked with the Four Color Theorem.

Gerhard Ringel

Although born in Austria, Ringel was raised in Czechoslovakia and attended Charles University before being drafted into the Wehrmacht in 1940 (after Germany had taken control of much of what had been Czechoslovakia). After the war Ringel served for over four years in a Soviet prisoner of war camp.[1]

He earned his Ph.D. from the University of Bonn in 1951 with a thesis written under the supervision of Emanuel Sperner and Ernst Peschl.[2] 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 continued his career at the University of California, Santa Cruz, having been invited there by his coauthor, John W. T. (Ted) Youngs. He was awarded honorary doctorate degrees from the Karlsruhe Institute of Technology and the Free University of 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.[3]

Publications
  • Ringel, Gerhard; Youngs, J.W.T. (1968). "Solution of the Heawood map-coloring problem". Proceedings of the National Academy of Sciences of the United States of America. 60 (2): 438–445. doi:10.1073/pnas.60.2.438. MR 0228378. PMC 225066. PMID 16591648.
  • Ringel, Gerhard (1974). Map Color Theorem. New York-Berlin: Springer-Verlag.[4]
  • Hartsfield, Nora; Ringel, Gerhard (1990). Pearls in graph theory. Boston, MA: Academic Press. ISBN 0-12-328552-6.
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gollark: "Features:- Fortunes/Dwarf Fortress output/Chuck Norris jokes on boot (wait, IS this a feature?)- (other) viruses (how do you get them in the first place? running random files like this?) cannot do anything particularly awful to your computer - uninterceptable (except by crashing the keyboard shortcut daemon, I guess) keyboard shortcuts allow easy wiping of the non-potatOS data so you can get back to whatever nonsense you do fast- Skynet (rednet-ish stuff over websocket to my server) and Lolcrypt (encoding data as lols and punctuation) built in for easy access!- Convenient OS-y APIs - add keyboard shortcuts, spawn background processes & do "multithreading"-ish stuff.- Great features for other idio- OS designers, like passwords and fake loading (est potatOS.stupidity.loading [time], est potatOS.stupidity.password [password]).- Digits of Tau available via a convenient command ("tau")- Potatoplex and Loading built in ("potatoplex"/"loading") (potatoplex has many undocumented options)!- Stack traces (yes, I did steal them from MBS)- Backdoors- er, remote debugging access (it's secured, via ECC signing on disks and websocket-only access requiring a key for the other one)- All this useless random junk can autoupdate (this is probably a backdoor)!- EZCopy allows you to easily install potatOS on another device, just by sticking it in the disk drive of any potatOS device!- fs.load and fs.dump - probably helpful somehow.- Blocks bad programs (like the "Webicity" browser).- Fully-featured process manager.- Can run in "hidden mode" where it's at least not obvious at a glance that potatOS is installed.- Convenient, simple uninstall with the "uninstall" command.- Turns on any networked potatOS computers!- Edits connected signs to use as ad displays.- A recycle bin.- An exorcise command, which is like delete but better.- Support for a wide variety of Lorem Ipsum."
gollark: You would need to get rid of the autoupdate capabilities of potatOS itself, or swap them to your own pastebins/github stuff, and then keep everything in line with the current versions.
gollark: Anyway, <@151391317740486657>, what you can do is fork potatOS and get rid of the bits you don't like, but that's also hard (less, though) and would be very difficult to keep updated.
gollark: That doesn't count.

References
  1. Bodendiek, Rainer; Henn, Rudolf, eds. (1990). Topics in Combinatorics and Graph Theory. Essays in Honour of Gerhard Ringel (PDF). Heidelberg: Physica-Verlag HD. doi:10.1007/978-3-642-46908-4. ISBN 978-3-642-46910-7. MR 1100014.
  2. Gerhard Ringel at the Mathematics Genealogy Project
  3. Retired mathematics professor Gerhard Ringel gives his world-class butterfly collection to UCSC Archived 2012-03-05 at the Wayback Machine, UC Santa Cruz Review, Fall 2006
  4. Kleitman, Daniel (1975). "Review: Map color theorem by Gerhard Ringel" (PDF). Bulletin of the American Mathematical Society. 81 (4): 657–660. doi:10.1090/s0002-9904-1975-13811-0.
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