Re:Tetrachromats: people who see colors invisible to most of...
by OJFord on Monday November 18, 2019 @02:50PM
(#21567520)
I know it's not about actual colours, I did say it was off-topic. :)
Re proving any, I replied to a sibling comment. What I was imagining was the inverse - proving that you can't construct one that requires a fifth.
Proving some maps can't be colored with three colors is easy, you only need to find one and enumerate all the three-colorings and find none of them work.
It's not really a theorem about colors though, they're just labels.