Four Corners and the Four Color Map Theorem

Factual Questions
1

On a website about my home state of Colorado, it lists Arizona as bordering it (at the CO/UT/AZ/NM Four Corners point).

But for purposes of map coloring, they aren’t considered bordering. Otherwise, the 4CMT would fail if you have 5 or more states meeting at a corner.

So, do Colorado and Arizona (or Utah and New Mexico) border each other or not?

Everybody got to elevate from the norm - Rush

2

For purposes of map coloring and the four color theorem, two “countries” must share an edge not just a single point.

You are correct if “countries” sharing a single point were considered sharing a border, then there would be no upper limit on the number of colors necessary.

Virtually yours,

DrMatrix