Kenneth Ira Appel (October 8, 1932 – April 19, 2013) was an American 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.[citation needed]

Quick facts: Kenneth Appel, Born, Died, Citizenship, Alma&...
Kenneth Appel
Kenneth Ira Appel

(1932-10-08)October 8, 1932
DiedApril 19, 2013(2013-04-19) (aged 80)
Alma materB.S.Queens College, CUNY
Ph.D.University of Michigan
Known forProving the Four-color theorem with Wolfgang Haken
ChildrenAndrew Appel[1]
Peter H. Appel[1]
AwardsFulkerson Prize [1979]
Scientific career
FieldsGraph theory, combinatorics, topology
InstitutionsUniversity of Illinois at Urbana–Champaign, University of New Hampshire
Doctoral advisorRoger Lyndon

Oops something went wrong: