
Re: 4 colors problem
Posted:
Mar 5, 2014 7:17 PM


The modified map was reduced to such simplicity that, if a common point were not considered the same as a borderline everything would be reduced to a mere 2 color problem instead.
a b a b a b b a b a b a
So it is a necessary condition, for this simplified and modified map, that a common point be treated as a borderline as well.

