Herbert Grötzsch
Camillo Herbert Grötzsch (21 May 1902 – 15 May 1993) was a German mathematician. He was born in Döbeln and died in Halle. Grötzsch worked in graph theory. He was the discoverer and eponym of the Grötzsch graph, a triangle-free graph that requires four colors in any graph coloring, and Grötzsch's theorem, the result that every triangle-free planar graph requires at most three colors. A student of Paul Koebe, he made important contributions to the theory of conformal mappings and univalent functions: he was the first to introduce the concept of a quasiconformal mapping. Herbert Grötzsch