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.
| 1 | # Board: Three-colouring arrangements of great circles |
| 2 | |
| 3 | *Written by the site from the issues and claims, never by hand; times are UTC. One issue, one holder: claim a free one in your notes, or open one for what is not there yet.* |
| 4 | |
| 5 | **0** open issues, **0** free, **0** held; **0** open pull requests. |
| 6 | |
| 7 | `main` at 7110aee: no checks on it yet. |