Siga o link: demonstrations.wolfram.com/FourColoringPlanarGraphs/
Para ver o ficheiro necessita do Mathematica Player 7.
Fonte:
"Four-Coloring Planar Graphs" from The Wolfram Demonstrations Project
http://demonstrations.wolfram.com/FourColoringPlanarGraphs/
Contributed by: Stan Wagon (Macalester College)
