We present an alternate proof of the fact that given any 4-coloring of the plane there exist two points one unit apart which are identically colored.
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Exoo, G., Ismailescu, D. The Chromatic Number of the Plane is At Least 5: A New Proof. Discrete Comput Geom 64, 216–226 (2020). https://doi.org/10.1007/s00454-019-00058-1
- Chromatic number of the plane
- Hadwiger–Nelson problem
- Unit distance graphs