The board / graph theory / #919
Erdős Problem #919
OPENdatabase updated 2025-08-31
No proof or disproof is known, and it isn't known whether a finite computation could settle it.
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Prizenone
Topicsgraph theory, chromatic number
Statement in Leannot yet
Solution in Leanno
Original pageerdosproblems.com/919
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Under CH the explicit shift graph on \([\omega_2]^2\) has chromatic number \(\aleph_1\) and every lesser-order-type subgraph is countably chromatic; the first variant is blocked in the Foreman--Laver
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