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...

conjecture was formulated in 1890 by P.J. Heawood and proven in 1968 by Gerhard Ringel and J.W.T. Youngs. One case, the non-orientable Klein bottle, proved...

prevention Faye Ringel, former American professor of humanities at the United States Coast Guard Academy and an author Gerhard Ringel (1919–2008), German...

coloring problem (solved by the four color theorem), and was posed by Gerhard Ringel in 1959. An intuitive form of the problem asks how many colors are needed...

graph theory is the graceful tree conjecture or Ringel–Kotzig conjecture, named after Gerhard Ringel and Anton Kotzig, and sometimes abbreviated GTC....

problem on the chromatic number of biplanar graphs, posed in 1959 by Gerhard Ringel, and on a related 1962 conjecture of Frank Harary: For any graph on...

combinatorics and graph theory. The Ringel–Kotzig conjecture on graceful labeling of trees is named after him and Gerhard Ringel. Kotzig's theorem on the degrees...

undergraduate-level textbook on graph theory by Nora Hartsfield and Gerhard Ringel. It was published in 1990 by Academic Press with a revised edition in...

conjectures (now theorems). Bernhard Riemann 24900 Ringel–Kotzig conjecture graph theory Gerhard Ringel and Anton Kotzig 187 Rudin's conjecture additive...

explicit use of homology. Sperner's students included Kurt Leichtweiss and Gerhard Ringel. Ein Satz über Untermengen einer endlichen Menge. Math. Z. 27 (1928)...

Heawood in 1890 and, after contributions by several people, proved by Gerhard Ringel and J. W. T. Youngs in 1968. The only exception to the formula is the...

never exceeds 6 {\displaystyle 6} . Later it was proved in the works of Gerhard Ringel, J. W. T. Youngs, and other contributors that the complete graph with...

Derek Dougan, Northern Irish footballer and manager (b. 1938) 2008 – Gerhard Ringel, Austrian mathematician and academic (b. 1919) 2009 – Roméo LeBlanc...

Reingold Jennifer Rexford Dana S. Richards Frigyes Riesz John Rigby Gerhard Ringel Alexander Rinnooy Kan John Riordan Jorma Rissanen Ivan Rival Ron Rivest...

Berlekamp, John L. Selfridge, Kenneth Falconer, Frank Harary, Lee Sallows, Gerhard Ringel, Béla Bollobás, C. B. Lacampagne, Bruce Sagan, and Neil Sloane. Over...

Research Institute for Mathematics, where the problem was posed in 1967 by Gerhard Ringel. It is known to be true for all sufficiently-large complete graphs....

discovered until eleven years after publication, nearly simultaneously by Gerhard Ringel and Paul Kainen. Nevertheless, it is conjectured that Zarankiewicz's...

the concept was already extensively used under the name "rotation" by Gerhard Ringel and J.W.T. Youngs in their famous solution of the Heawood map-coloring...

17 percent of the municipality is forested. Bad Pirawarth Kollnbrunn Gerhard Ringel, born at Kollnbrunn "Dauersiedlungsraum der Gemeinden Politischen Bezirke...

molecule with a grant from the National Institutes of Health. For Dr. Gerhard Ringel, head of the Math department at UCSC, Risan worked on embeddings on...

Richarz Eugen Richter Hans Riegel Charles Pierre Henri Rieu Matthias Ring Gerhard Ringel Albrecht Ritschl Otto Ritschl Franz Ritter Emil Ritterling Robert Kurt...

magic square is semimagic, but not vice versa. Nora Hartsfield and Gerhard Ringel (1994, 2003), Pearls in Graph Theory, revised edition. Dover Publications...

with Robert Adams), Galerie Thomas Zander, Köln; Lagune, Galerie Felix Ringel, Düsseldorf; Journal Entries, Heni Publishing, London 2019: deeply unaware...

problem for Frechét Surfaces, Memoirs American Mathematical Society 1951 Ringel, Gerhard; Youngs, J.W.T. (1968). "Solution of the Heawood map-coloring problem"...

the proof of the Heawood conjecture on coloring graphs on surfaces by Gerhard Ringel and Ted Youngs. And Günter M. Ziegler complains that many claims are...

39 (1): 3–6, hdl:10338.dmlcz/136481, MR 1016323 Hartsfeld, Nora; Ringel, Gerhard (1991), "Clean triangulations", Combinatorica, 11 (2): 145–155, doi:10...

"natives" anyway as some had joined Saarland clubs from elsewhere, like Ringel, Immig or goalkeepers Borcherding and Jirasek; see List of Saarland international...

1954 to 1965. In 1965 Günther Nenning took over as editor and in 1986 Gerhard Oberschlick. The magazine was distributed internationally and instigated...

the town of Santhià, on the way to Milan, resulting in 48 deaths. Julius Ringel (1 November 1940 – 10 February 1944) Max-Günther Schrank (10 February 1944...

Three of the Saar team's players later represented Germany: Karl Ringel, Gerhard Siedl and Heinz Vollmar. Upon Germany's reunification in 1990, the...