I was born in Brooklyn, the son of an electrical engineer and an office worker.
After receiving my undergraduate math degree from Queens College, I became an actuary, served in the army, and eventually obtained a Ph.D. in mathematics from the University of Michigan.
After programming computers in 1959 for Douglas Aircraft and being a cryptologist for the Institute of defense Analysis, I became a math professor at the University of Illinois.
My mathematics research focused on group theory, topology, and computability theory.
Working with a colleague, we were able to use computers to solve the famous Four Color Map problem, first posed by English mapmaker Francis Guthrie in 1852.
The proof was by "exhaustion of cases" using 1200 hours of computation time (i.e. 50 days) and 10 billion logical decisions...something that bothered the mathematics community, who felt a mathematical proof had to be done and verified by human hands.
My reaction to the proof controversy: "Without computers, we would be stuck only proving theorems that have short proofs!"
Kenneth Appel (1932 - 2013)