Description: Papers of Kenneth Appel (1932-2013), professor of mathematics (1961-93), includes correspondence, research notes, drafts, publicity material, computer punch cards, and data printouts relating to the Four Color Theorem and the Poincare Conjecture.
The Four Color Theorem was proved in the year of 1976 at the University of Illinois at Urbana-Champaign by Kenneth Appel and Wolfgang Haken, stating that any planar map can be colored with no more than four colors. It was one of the first computer aided proofs.
Significant correspondents include Wolfgang Haken, Martin Gardner, and Jean Mayer.