Gerhard Ringel was a German

Germans

The Germans are a Germanic ethnic group native to Central Europe. The English term Germans has referred to the German-speaking population of the Holy Roman Empire since the Late Middle Ages....

 mathematician

Mathematician

A mathematician is a person whose primary area of study is the field of mathematics. Mathematicians are concerned with quantity, structure, space, and change....

 who earned his Ph.D. from the University of Bonn

University of Bonn

The University of Bonn is a public research university located in Bonn, Germany. Founded in its present form in 1818, as the linear successor of earlier academic institutions, the University of Bonn is today one of the leading universities in Germany. The University of Bonn offers a large number...

 in 1951. He was one of the pioneers in graph theory

Graph theory

In mathematics and computer science, graph theory is the study of graphs, mathematical structures used to model pairwise relations between objects from a certain collection. A "graph" in this context refers to a collection of vertices or 'nodes' and a collection of edges that connect pairs of...

 and contributed significantly to the proof of the Heawood conjecture

Heawood conjecture

In graph theory, the Heawood conjecture or Ringel–Youngs theorem gives a lower bound for the number of colors that are necessary for graph coloring on a surface of a given genus. It was proven in 1968 by Gerhard Ringel and John W. T. Youngs. One case, the non-orientable Klein bottle, proved an...

 (now the Ringel-Youngs theorem), a mathematical problem closely linked with the Four Color Theorem

Four color theorem

In mathematics, the four color theorem, or the four color map theorem states that, given any separation of a plane into contiguous regions, producing a figure called a map, no more than four colors are required to color the regions of the map so that no two adjacent regions have the same color...

.

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

German student movement

The German student movement was a protest movement that took place during the late 1960s in West Germany. It was largely a reaction against the perceived authoritarianism and hypocrisy of the German government and other Western governments, and the poor living conditions of students...

, and continued his career at the University of California, Santa Cruz

University of California, Santa Cruz

The University of California, Santa Cruz, also known as UC Santa Cruz or UCSC, is a public, collegiate university; one of ten campuses in the University of California...

. 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

University of California, Santa Cruz

The University of California, Santa Cruz, also known as UC Santa Cruz or UCSC, is a public, collegiate university; one of ten campuses in the University of California...

Museum of Natural History Collections.

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