Kenneth Appel (born 1932) is a mathematician who, in 1976 with colleague Wolfgang Haken at the University of Illinois at Urbana-Champaign, solved one of the most famous problems in mathematics, the four-color theorem. They proved that any two-dimensional map, with certain limitations, can be filled in with four colors without any adjacent "countries" sharing the same color. Appel's children, including Laurel Appel, Peter Appel, and Andrew Appel, now a professor at Princeton, helped in the checking of over 1000 topological cases that constitute this proof. Year 1932 (MCMXXXII) was a leap year starting on Friday (the link will display full 1932 calendar) of the Gregorian calendar. ... Year 1976 (MCMLXXVI) was a leap year starting on Thursday (link will display full calendar) of the 1976 Gregorian calendar. ... Wolfgang Haken (born June 21, 1928) is a mathematician who specialized in topology, in particular 3-manifolds. ... The University of Illinois at Urbana-Champaign (UIUC), is the largest campus in the University of Illinois system. ... Euclid, Greek mathematician, 3rd century BC, as imagined by by Raphael in this detail from The School of Athens. ... Example of a four color map The four color theorem states that every possible geographical map can be colored with at most four colors in such a way that no two adjacent regions receive the same colour. ... As of 2004, Andrew W. Appel is a professor of computer science at Princeton University. ...

The proof has been one of the most controversial of modern mathematics because of its heavy dependence on computer "number-crunching" to sort through possibilities. Even Appel has agreed, in numerous interviews, that it lacks elegance and provided no new insight that has guided future mathematical research.

Others, however, have pointed to this work as the start of a sea-change in mathematicians' attitudes toward computers - which they had largely disdained as a tool for engineers rather than for theoreticians - leading to the creation of what is sometimes called "experimental mathematics."

From 1993 through 2002, Appel was head of the mathematics department at the University of New Hampshire in Durham, New Hampshire. University of New Hampshire (UNH) is a public university in the University System of New Hampshire (USNH). ... Old mill and dam on the Oyster River, 1908, Durham, NH Durham is a town located in Strafford County, New Hampshire, USA. As of the 2000 census, the town had a total population of 12,664. ...