The four color problem gets a sharp new hue

Mathematicians find new answers to the still puzzling theorem that four colors suffice to color any map.

By Julie Rehmeyer, 15:19 PM March 6, 2009

In 1852, botanist Francis Guthrie noticed something peculiar as he was coloring a map of counties in England. Despite the counties’ meandering shapes and varied configurations, four colors were all he needed to shade the map so that any two bordering counties were different colors. Perhaps, he speculated, four colors were enough for any map.

Little did Guthrie know the load of trouble he unleashed with his innocent conjecture. It took mathematicians nearly a century and a quarter to prove h...

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