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Nashua;83.0;http://forecast.weather.gov/images/wtf/small/few.png;2014-09-01 19:21:34
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Four colors is sufficient to prevent colors from "bumping up" against each other, even in a weird "map" like this one.
Friday, April 26, 2013

Man who proved four-color map problem, ex-UNH math head, dies

Kenneth Appel, famous for being part of the team that created the first great computer-aided proof, of the "four-color" theorem which says that any map can be colored with four colors without bumping colors against each other, and who later headed up the UNH math department, has died. He was 80.

Here's an article I wrote about him and the proof for UNH Magazine in 2002.

The four-color proof was controversial because it dependend on a computer to crank through many possibilities as a demonstration that any possible map can be colored with just four colors without have any two adjacent shapes be the same color. It was the first major proof that couldn't be totally understood by a human, and when released in 1976 (a time when mathematics still shunned computers as mere arithmetic tools) it drew howls of outrage.

Even Appel and his colleague Wolfgang Haaken (both at the U. of Illinois at the time) agreed it wasn't elegant. My favorite comment came from one mathematician who said something along the lines of: "that just shows it wasn't an interesting question after all."

The issue is so important and interesting that I own no less than three books entirely about the four-color problem - two written before the proof, one after it.

Appel came to UNH later in life. I first interviewed him for The Telegraph so long ago that the article wasn't digitized - I'll have to dig up paper clips - and he was still slightly defensive about the whole thing.

Here's the only online source I can find which acknowledges his death. It also discusses the four-color problem. UNH, so far as I know, hasn't said anything.