Journal of the Mathematics Council of the Alberta Teachers’ Association
Volume 37 Issue 2, June 2000
68
Klaus Puhlmann
The renowned conjecture in topology that arose circa 1852 asserts that four colors are both sufficient and necessary for coloring all maps drawn on a plane or sphere so that no two regions that touch (that is, share a segment of a boundary) are the same color. While this conjecture has always been an accepted fact for cartographers, for mathematicians it remained an unproved supposition.
