**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 | |
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Born | Kenneth Ira Appel October 8, 1932 |

Died | April 19, 2013 80) | (aged

Citizenship | American |

Alma mater | B.S. – Queens College, CUNY Ph.D. – University of Michigan |

Known for | Proving the Four-color theorem with Wolfgang Haken |

Children | Andrew Appel[1] Peter H. Appel[1] |

Awards | Fulkerson Prize [1979] |

Scientific career | |

Fields | Graph theory, combinatorics, topology |

Institutions | University of Illinois at Urbana–Champaign, University of New Hampshire |

Doctoral advisor | Roger Lyndon |

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