Francis Guthrie

Francis Guthrie was a Cape Colony mathematician and botanist who first posed the Four Colour Problem in 1852. He studied mathematics under Augustus De Morgan, and botany under John Lindley at University College London. Guthrie obtained his B.A. in 1850, and LL.B. in 1852 with first class honours. While colouring a map of the counties of England, he noticed that at least four colours were required so that no two regions sharing a common border were the same colour. He postulated that four colours would be sufficient to colour any map. This became known as the Four Color Problem, and remained one of the most famous unsolved problems in graph theory for more than a century until it was eventually proven in 1976 using a lengthy computer-aided proof by Appel and Haken.