Tag Archives: Graph theory

I moved the code under github


I moved all code under github here: https://github.com/stefanutti I organized the folders a little betters (different github repos) I’m experimenting docker to deliver & deploy the Java and Python software I’ll also try to integrate a deep learning module, based on … Continue reading

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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

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Four color theorem: back to the basics


Finally I bought two books about the four color theorem: “Four Colors Suffice: How the Map Problem Was Solved” by Robin Wilson e Ian Stewart; and the “The Four-Color Theorem: History, Topological Foundations, and Idea of Proof” by Rudolf Fritsch and Gerda Fritsch. I’am in … Continue reading

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Four color theorem: work in progress


😦 Too many more things to do and little time: Filter out duplicates. I finally found a java library to efficiently filter out all isomorphic graphs. It is a library part if the sspace project. Using it I will be able … Continue reading

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Four color theorem: Cahit spiral chains


Hi, I’ve found some time to implement the first version of Cahit Spiral Chains algorithm. I still need to: Find all spiral chains of a given graph and not only one (changing the starting point) I need to implement the … Continue reading

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Four color theorem: Tait edge coloring video


And here is the video that shows how to get a Tait colored map (graph) from a rectangular map.

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Four color theorem: Tait edge coloring


From Wikipedia: “The four color theorem, on vertex coloring of planar graphs, is equivalent to the statement that every bridgeless 3-regular planar graph is of class one (Tait 1880). This statement is now known to be true, due to the … Continue reading

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