Tag Archives: Kempe

Four color theorem: new ideas


This is what I want to try: Select an F2, F3  or F4 preferably when it is near an F5 and remove the edge that joins the two faces Analyse also the balance of the Euler’s identity when removing edges, to … Continue reading

Posted in math | Tagged , | 1 Comment

Four color theorem: what next?


The algorithm I use to color graphs works pretty well … BUT: Sometimes (very rarely) it gets into an infinite loop where also random Kempe color switches (around the entire graph) do NOT work. The good is, if I reprocess … Continue reading

Posted in math | Tagged , , , , | Leave a comment

Four color theorem: one switch is not enough :-(


Experimenting with the Python program, I have found that if you have an F5 impasse, a single switch may not be enough to solve the impasse. It means: counterexample found. This is a bad news, since I believed that a … Continue reading

Posted in math | Tagged , , , | Leave a comment

Four color theorem: down to a single case!


This post follows directly the previous one. I’m down to a single case to prove (pag. 3). I think I should move to Java coding, implementing the entire algorithm: map reduction (removing edges), color reduced map, restore of edges one at a … Continue reading

Posted in math | Tagged , , , , , | Leave a comment