Apologies if this noddy q has been covered before. What are the most recent, and 'best', accepted proofs of the 4C Theorem? The proof by Robertson, Sanders, Seymour and Thomas (1996) has been published in a reputable journal, seems to be leaner and make more use of formal proofs than Appel/Haken/Koch (1977), and presumably is accepted. I see references to a proof by Ashay Dharwadker (2000). Has this been accepted or refuted? Guy