Editing Kenneth Appel (section)

{{short description|American mathematician (1932–2013)}}
{{Infobox scientist
| birth_name        = Kenneth Ira Appel
| image             = Kenneth appel 1970.jpg
| caption           = Appel in 1970
| birth_date        = {{Birth date|1932|10|8}}
| birth_place       = [[Brooklyn]], [[New York (state)|New York]]
| death_date        = {{death date and age|2013|04|19|1932|10|8}}
| death_place       = [[Dover, New Hampshire]]
| citizenship       = [[United States of America|American]]
| ethnicity         = 
| fields            = [[Graph theory]], [[combinatorics]], [[topology]]
| workplaces        = [[University of Illinois at Urbana–Champaign]], [[University of New Hampshire]]
| alma_mater        = [[B.S.]] – [[Queens College, City University of New York|Queens College, CUNY]]<br />[[Doctor of Philosophy|Ph.D.]] – [[University of Michigan]]
| doctoral_advisor  = [[Roger Lyndon]]
| doctoral_students = <!-- [[Weldon Bliss]]<br />[[Jo Ann Fellin]]<br />[[Everett Gibson]]<br />[[Zhu-Xin Hu]]<br />[[John Koch]] -->
| known_for         = Proving the [[Four-color theorem]] with [[Wolfgang Haken]]
| influences        = 
| influenced        = 
| awards            = [[Fulkerson Prize]] [1979]
| signature         = <!--(filename only)-->
| footnotes         = 
| children          = [[Andrew Appel]]<ref name="memoriam">{{Cite web|last=|first=|date=|title=In Memoriam: Kenneth Appel|url=https://math.illinois.edu/resources/department-history/faculty-memoriam/kenneth-appel|archive-url=https://web.archive.org/web/20211201130155/https://math.illinois.edu/resources/department-history/faculty-memoriam/kenneth-appel|archive-date=2021-12-01|access-date=2020-09-07|website=math.illinois.edu}}</ref><br />
[[Peter H. Appel]]<ref name="memoriam" />
}}

'''Kenneth Ira Appel''' (October 8, 1932 – April 19, 2013) was an [[Americans|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 problems in [[mathematics]]. 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. The proof was controversial because it depended on thousands of computer calculations that could not be double-checked by hand, the first prominent example of such a process.