Kenneth Appel

Kenneth Ira Appel , also Ken Appel (born October 8, 1932 in Brooklyn , New York City , † April 19, 2013 in Dover , New Hampshire ), was an American mathematician , who mainly because of his proof of the four-color theorem with Wolfgang Haken 1976 is known.

Appel studied at Queens College (bachelor's degree) until 1953, served two years in the US Army and then continued his studies at the University of Michigan , where he worked with Roger Lyndon in 1959 with the dissertation Two Investigations on the Borderline of Logic and PhD in algebra .

He then worked for two years at the Institute for Defense Analyzes in Princeton and then went to the University of Illinois at Urbana-Champaign as an assistant professor in 1961 , where he became associate professor in 1967 and full professor in 1977, and where he and Wolfgang in 1976 Hook proved the famous four-color theorem. This means that for every two-dimensional map (with certain restrictions) four colors are sufficient to color the map without neighboring "countries" being the same color.

The proof only came about through massive computer use and could only be verified by computer (around 1500 individual cases had to be checked). In terms of evidence, it marks a turning point in the history of mathematics - the beginning of what is known today as experimental mathematics . In their proof, they built on ideas from Heinrich Heesch , who in the 1960s also worked on a proof with computer assistance at the TU Hannover , but received insufficient financial support and was otherwise relatively isolated. For their proof, Appel and Haken needed 1200 hours of computing time on an IBM 360 with 64 kB of working memory, which was otherwise only used for administrative purposes at the university. Their work on the proof took about four years and began in 1972. They were also supported by the children of Appel (his son Andrew is now also a professor of computer science at Princeton). In celebration of the evidence, the University of Illinois introduced a new postmark, Four colors suffice . Apparently, most of the programming (in assembly language) was done by Appel, while the topologist Haken contributed conceptual ideas.

Kenneth Appel was most recently professor at the University of New Hampshire in Durham, where he was head of the mathematics department from 1993 to 2002. He is a fellow of the American Mathematical Society .

In 1979 he received the AMS Fulkerson Prize for discrete mathematics with Haken .

He was married to Carole Stein since 1959.

literature

Appel, Haken: Every planar map is four colorable. Part I. Discharging . Illinois Journal of Mathematics Vol. 21, 1977
Appel, Haken: Every planar map is four colorable , Bulletin AMS Vol. 82, 1976, p. 711
Appel, Haken: Every Planar Map is Four Colorable , Contemporary Mathematics, Vol. 98, American Mathematical Society, 1989
Appel, Haken: The Solution of the Four-Color-Map Problem , Scientific American, Vol. 237, No. 4, pp. 108-121 (1977)
Robin Wilson : Four Colors Suffice: How the Map Problem Was Solved , Princeton University Press, Penguin Books 2002

Web links

personal data
SURNAME	Appel, Kenneth
ALTERNATIVE NAMES	Appel, Ken
BRIEF DESCRIPTION	American mathematician
DATE OF BIRTH	October 8, 1932
PLACE OF BIRTH	Brooklyn , New York City
DATE OF DEATH	April 19, 2013
Place of death	Dover, New Hampshire