Herbert Grötzsch

Camillo Herbert Grötzsch was a German mathematician known primarily for his work on complex analysis, specifically univalent functions and conformal mappings, and graph theory. He was the first to introduce the concept of a quasiconformal mapping. 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.