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Multicolour Triangle Ramsey Numbers (Erdős #183)
AI-resolved
Posed by Paul Erdős · 1970 · Ramsey theory · resolved 2026
The problem
Let \(R_{k}\)(3) be the least n such that any k-colouring of the edges of \(K_{n}\) yields a monochromatic triangle. Erdős asked how fast \(R_{k}\)(3) grows; the conjectured lower-bound mechanism (probabilistic) gave roughly c·k! growth. Erdős problem #183 asks for a superexponential construction.
References
History & significance
Ramsey numbers are notoriously resistant: even R(5,5) is unknown between 43 and 48. The multicolour triangle function was pinned between exponential and factorial bounds for decades, with improvements measured in constant factors.
The resolution (solved by AI)
Resolved by OpenAI's Astra model, 1 August 2026: a superexponential lower bound for multicolour triangle Ramsey numbers, settling Erdős problem #183. Listed among the ten advances alongside resolutions of Erdős problems #146 and #180 (compactness/degeneracy in extremal graph theory) — three catalogue entries of Bloom's database retired in one batch.
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