Can every map be colored with just four colors so that no two adjacent regions have the same color?

Answer 1

Yes, the Four Color Theorem proves that every map can be colored with just four colors so that no two adjacent regions have the same color. This theorem was first stated in 1852 and was finally proven in 1976 by Kenneth Appel and Wolfgang Haken using computer-assisted methods. The theorem applies to planar maps, which are maps that can be represented on a flat surface without any regions overlapping.