Stackexchange
Last visits
Comments
Anonymous on Color Voronoi graphs Anonymous on Detailed history Tyson on Four color theorem: almost… Richard Eicholtz on Introduction Richard Eicholtz on Introduction Richard Eicholtz on Detailed history Richard Eicholtz on Introduction Richard Eicholtz on Introduction Richard Eicholtz on Detailed history stefanutti on Detailed history
Tag Archives: Tait coloring
Non-Hamiltonian 3-regular planar graphs, Tait coloring and Kempe cycles … what else ;-)
Non Hamiltonian 3-regular planar graphs, Tait coloring and Kempe loops. Continue reading
Tait coloring and the four color theorem: personal Q&A
Connections between the Tait coloring of a map and the Four Color Theorem. Continue reading
Posted in math
Tagged 4ct, four color theorem, pencil and paper, proof, Tait coloring
Leave a comment
New paths for the 4ct?
About the four color theorem, Tait coloring of the borders has color chains (R-G or R-B or G-B) that always form loops. Continue reading
Euler’s formula at work
This video shows how the Euler’s equation redistribute its weights during the reduction process of a planar cubic graph, related to the four color theorem and a modified version of the Kempe reduction process. Continue reading
Zoom on a planar graph, 10000 nodes, three-edge Tait colored
Zoom on a planar graph, 10000 nodes, three-edge Tait colored related to the four color theorem Continue reading
Posted in math
Tagged Alfred Bray Kempe, four color theorem, Kempe chain, Tait coloring
Leave a comment
Four color theorem: A fast algorithm – 2
Four color theorem: A fast algorithm These are the OLD and NEW (last column) execution times on my new laptop: 100 – 196 vertices, 294 edges = 0 seconds – 0 seconds 200 – 396 vertices, 594 edges = 1 seconds – 0 seconds 300 … Continue reading
Four color theorem: Infinite switches are not enough – Rectangular maps :-(
I transformed the really bad case into a rectangular map to play with the Java program and Kempe random switches. Here is the graph with the two edges to connect: The two edges marked with the X, have to be … Continue reading
Four color theorem: Infinite switches are not enough :-( :-(
A new edge 12-7 that connects the edges 6-10 and 32-15. With this case seems that infinite random switches throughout the entire graph do not solve the impasse, which is really really really bad.
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
Four Color Theorem blog 