The four-color theorem states that any map in a plane can be colored using four colors in such a way that regions sharing a common boundary (other than a single point) do not share the same color.

Guthrie's problem

formulation date | 1852 (173 years ago) formulator | Francis Guthrie status | proved proof date | 1977 (125 years later) (48 years ago) provers | Kenneth Appel | Wolfgang Haken

solved mathematics problems | mathematics theorems