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| | The 4 Color Map Problem |
 | | A summary of a new proof and a coloring algorithm, by Neil Robertson, Daniel P. Sanders, Paul Seymour and Robin Thomas. |
 | | In 1878 the mathematician Arthur Cayley presented the problem to the London Mathematical Society. |
 | | In 1852, Francis Guthrie wrote to his brother Frederick saying it seemed that four colors were always sufficient, did Frederick know a proof. |
| www.math.utah.edu /~alfeld/math/4color.html (309 words) |
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