Four colors can color two-dimensional maps so no two countries with common boundary have same color {map problem} {four-color theorem}|. Kenneth Appel and Wolfgang Haken proved the four-color theorem [1976], by enumerating possibilities and then checking all by computer. One-dimensional line maps need two colors. Three-dimensional maps need six colors.
Mathematical Sciences>Topology>Problems>Map
Outline of Knowledge Database Home Page
Description of Outline of Knowledge Database
Date Modified: 2022.0224