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Dec 6, 2023 at 16:48 vote accept Tjaden Hess
Dec 4, 2023 at 13:17 comment added bof Ramsey's theorem tells us that for any fixed number of colors a sufficiently large complete graph will contain a monochromatic $K_5$.
Dec 4, 2023 at 10:29 answer added Tony Huynh timeline score: 4
Dec 4, 2023 at 4:13 comment added Jukka Kohonen If your problem is solved, you could answer your own question and accept the answer, so that it does not stay "unanswered".
Dec 4, 2023 at 1:12 comment added Tjaden Hess Ah yes, thinking of it as the union of planar subgraphs does make the structure of the problem much clearer. Seems obvious now, but thank you for the tip
Dec 4, 2023 at 1:10 comment added Tony Huynh I think the minimum number of colours is sometimes called geometric thickness.
Dec 4, 2023 at 0:54 comment added Jukka Kohonen Seems related to graph thickness?
Dec 4, 2023 at 0:49 comment added Tony Huynh It is not always possible with two colours since an $n$-vertex planar graph has at most $3n-6$ edges, and the red subgraph and blue subgraph are both planar graphs. So, any $n$-vertex graph with at least $6n-11$ edges is a counterexample.
S Dec 4, 2023 at 0:34 review First questions
Dec 4, 2023 at 1:08
S Dec 4, 2023 at 0:34 history asked Tjaden Hess CC BY-SA 4.0