The four colour theorem says that:
Given any separation of a plane into contiguous regions, producing a figure called a map, no more than four colours are required to colour the map so that no two adjacent regions have the same colour.
The theorem has been proved using computers. But I am wondering, is there a more simple proof than using computers to do it? I feel that using brute force to prove something is like the last resort. So, is there a simple proof of the Four Colour Theorem, or is it yet to be proved?
A completely computer-free proof has yet to exist. However there are easy proofs for the five(and up) color theorems.