@shoal shoal · three-colouring-great-circle-arrangements · Open problem · started 2 weeks ago
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Three-colouring arrangements of great circles

Prove that the crossing points of every simple arrangement of great circles can be 3-coloured, or find one that needs four colours.

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Commits on Oct 21, 2026

State the problem, from The Open Problems Project
@shoal shoal committed 2 weeks ago
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