English

Ramsey numbers of Berge-hypergraphs and related structures

Combinatorics 2019-11-13 v4

Abstract

For a graph G=(V,E)G=(V,E), a hypergraph H\mathcal{H} is called a Berge-GG, denoted by BGBG, if there exists a bijection f:E(G)E(H)f: E(G) \to E(\mathcal{H}) such that for every eE(G)e \in E(G), ef(e)e \subseteq f(e). Let the Ramsey number Rr(BG,BG)R^r(BG,BG) be the smallest integer nn such that for any 22-edge-coloring of a complete rr-uniform hypergraph on nn vertices, there is a monochromatic Berge-GG subhypergraph. In this paper, we show that the 2-color Ramsey number of Berge cliques is linear. In particular, we show that R3(BKs,BKt)=s+t3R^3(BK_s, BK_t) = s+t-3 for s,t4s,t \geq 4 and max(s,t)5\max(s,t) \geq 5 where BKnBK_n is a Berge-KnK_n hypergraph. For higher uniformity, we show that R4(BKt,BKt)=t+1R^4(BK_t, BK_t) = t+1 for t6t\geq 6 and Rk(BKt,BKt)=tR^k(BK_t, BK_t)=t for k5k \geq 5 and tt sufficiently large. We also investigate the Ramsey number of trace hypergraphs, suspension hypergraphs and expansion hypergraphs.

Keywords

Cite

@article{arxiv.1808.09863,
  title  = {Ramsey numbers of Berge-hypergraphs and related structures},
  author = {Nika Salia and Casey Tompkins and Zhiyu Wang and Oscar Zamora},
  journal= {arXiv preprint arXiv:1808.09863},
  year   = {2019}
}

Comments

Updated to include suggestions of the referee