The board / graph theory / #149
Erdős Problem #149
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
Statement in Leannot yet
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Original pageerdosproblems.com/149
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A July 2026 strong-clique bound, specialized at maximum degree 4, proves the exact value 20; the C5 two-blowup attains it. This is a literature-derived partial. The strong chromatic maximum remains between 20 and 21, so Problem 149 is still open.
PARTIAL