For anyone interested, there's a really excellent book on the history of the problem as well as the AH proof, going into quite a lot of detail. Very highly reco

For anyone interested, there's a really excellent book on the history of the problem as well as the AH proof, going into quite a lot of detail. Very highly recommend. "Four Colors Suffice: How the Map Problem Was Solved" by Robin Wilson. https://www.goodreads.com/book/show/450635.Four_Colors_Suffice https://www.goodreads.com/book/show/450635.Four_Colors_Suffi...