The Kittell graph is a planar graph on 23 nodes and 63 edges that tangles the Kempe chains in Kempe's algorithm and thus provides an example of how Kempe's supposed proof of the four-color theorem fails.
Kempe, A. B. "On the Geographical Problem of Four-Colors." Amer. J. Math.2, 193-200, 1879.Kittell, I. "A Group of Operations on a Partially Colored Map." Bull. Amer. Math. Soc.41, 407-413, 1935.Wagon, S. Mathematica in Action, 2nd ed. New York: Springer-Verlag, pp. 533-534, 1999.
