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Name: yendor
Status: N/A
Age: N/A
Location: N/A
Country: N/A
Date: Around 1995

I heard that a computer has solved the famous four-color problem. I was wondering if someone could tell me why this is so. (The four-color problem is having to use four colors on a map so that no two colors that are the same are next to each other). I realize that for the two to be neighbors they must share infinitely many boundary points, but am still confused as to why this is true. Could someone tell me why you need four colors in either non mathematical or mathematical terms please.

A few years ago two mathematicians at the University of Illinois created a proof that any map can be colored with four colors (or fewer). The proof is VERY long and is a challenge to understand. It proceeds by first reducing the infinitely many possible maps to a finite number of special cases (still a lot of cases) and then, wit assistance of a computer, checking all of these cases. There was an article describing the method of proof in the Scientific American a few years ago. That would be a good place to start in studying the proof.


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