{ "domain": "mathematics", "topics": [ "discrete-geometry", "graph-theory" ], "type": "construction", "also": [ "proof" ], "cover": { "motif": "graph", "n": 7 }, "source": { "key": "erdos", "name": "Erdős Problems", "url": "https://www.erdosproblems.com/508", "id": "508", "curator": "Thomas Bloom", "poser": "Hugo Hadwiger and Edward Nelson", "status": "open", "as_of": "2026-10-20", "catalog": "0521c19bbd38" }, "review": true, "approval": "first-time" }