four color theorem

English

Example of a four-colored map

Map of the world using just four colors.

Proper noun

four color theorem

1. (graph theory) A theorem stating 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 so that no two adjacent regions have the same color (adjacent being defined as two regions sharing a boundary, not counting corners, in which three or more regions share a boundary).

Further reading

• Four color theorem on Wikipedia.Wikipedia