Four color theorem
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In mathematics, the four color theorem, or the four-color map theorem, states that no more than four colors are required to color the regions of any map so that no two adjacent regions have the same c
As they had with Donald Gillies' discovery of the then-largest prime number using ILLIAC II in 1963, the University of Illinois Urbana-Champaign Mathematics department celebrated the discovery of Appel and Haken's computer-aided proof of the Four color theorem by altering their postage meter.
Kenneth Appel
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Kenneth Ira Appel was an American mathematician who in 1976, with colleague Wolfgang Haken at the University of Illinois at Urbana–Champaign, solved the four-color theorem, one of the most famous prob
Four color theorem
…argument. Although the weaker five color theorem was proven already in the 1800s, the four color theorem resisted until 1976, when it was proven by Kenneth Appel and Wolfgang Haken in a computer-aided proof. This came after many false proofs and mistaken counterexamples in the preceding decades. The Appel–Haken…
Appel in 1970