English

Hypergraph Ramsey numbers of cliques versus stars

Combinatorics 2022-10-10 v1

Abstract

Let Km(3)K_m^{(3)} denote the complete 33-uniform hypergraph on mm vertices and Sn(3)S_n^{(3)} the 33-uniform hypergraph on n+1n+1 vertices consisting of all (n2)\binom{n}{2} edges incident to a given vertex. Whereas many hypergraph Ramsey numbers grow either at most polynomially or at least exponentially, we show that the off-diagonal Ramsey number r(K4(3),Sn(3))r(K_{4}^{(3)},S_n^{(3)}) exhibits an unusual intermediate growth rate, namely, 2clog2nr(K4(3),Sn(3))2cn2/3logn 2^{c \log^2 n} \le r(K_{4}^{(3)},S_n^{(3)}) \le 2^{c' n^{2/3}\log n} for some positive constants cc and cc'. The proof of these bounds brings in a novel Ramsey problem on grid graphs which may be of independent interest: what is the minimum NN such that any 22-edge-coloring of the Cartesian product KNKNK_N \square K_N contains either a red rectangle or a blue KnK_n?

Keywords

Cite

@article{arxiv.2210.03545,
  title  = {Hypergraph Ramsey numbers of cliques versus stars},
  author = {David Conlon and Jacob Fox and Xiaoyu He and Dhruv Mubayi and Andrew Suk and Jacques Verstraete},
  journal= {arXiv preprint arXiv:2210.03545},
  year   = {2022}
}

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13 pages