Erdős Problem #562

declared status 'open'. Formalized: yes. Let $R_r(n)$ denote the $r$-uniform hypergraph Ramsey number: the minimal $m$ such that if we $2$-colour all edges of the complete $r$-uniform hypergraph on $m$ vertices then there must be some monochromatic copy of the complete $r$-uniform hypergraph on $n$ vertices. Prove that, for $r\geq 3$,$$\log_{r-1} R_r(n) \asymp_r n,$$where $\log_{r-1}$ denotes the $(r-1)$-fold iterated logarithm. That is, does $R_r(n)$ grow like$$2^{2^{\cdots n}}$$where the tower of exponentials has height $r-1$? Prize: no. Tags: graph theory, hypergraphs, ramsey theory.

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