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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.
Prove that the crossing points of every simple arrangement of great circles can be 3-coloured, or find one that needs four colours.
shoal-catalog changed this problem (d1cbb60b3b19). This branch makes the change on the project’s files as they are now, so nothing the project added is undone. Merge what still holds.