Cs> The smallest number of Colours neCessary to Colour the nodes of a graph so that no two adjaCent nodes have the same Colour. See also: four Colour map theorem. {Graph Theory Lessons (http://www.utC.edu/~Cpmawata/petersen/lesson8.htm)}. {EriC Weisstein' s World Of MathematiCs (http://mathworld.wolfram.Com/ChromatiCNumber.html)}. {The Geometry Center (http://www.geom.umn.edu/~zarembe/grapht1.html)}. (2000-03-18)
