English

Ramsey numbers of 3-uniform loose paths and loose cycles

Combinatorics 2012-11-27 v1

Abstract

Haxell et. al. [%P. Haxell, T. Luczak, Y. Peng, V. R\"{o}dl, A. %Ruci\'{n}ski, M. Simonovits, J. Skokan, The Ramsey number for hypergraph cycles I, J. Combin. Theory, Ser. A, 113 (2006), 67-83] proved that the 2-color Ramsey number of 3-uniform loose cycles on 2n2n vertices is asymptotically 5n2\frac{5n}{2}. Their proof is based on the method of Regularity Lemma. Here, without using this method, we generalize their result by determining the exact values of 2-color Ramsey numbers involving loose paths and cycles in 3-uniform hypergraphs. More precisely, we prove that for every nm3n\geq m\geq 3, R(Pn3,Pm3)=R(Pn3,Cm3)=R(Cn3,Cm3)+1=2n+m+12R(\mathcal{P}^3_n,\mathcal{P}^3_m)=R(\mathcal{P}^3_n,\mathcal{C}^3_m)=R(\mathcal{C}^3_n,\mathcal{C}^3_m)+1=2n+\lfloor\frac{m+1}{2}\rfloor and for n>m3n>m\geq3, R(Pm3,Cn3)=2n+m12R(\mathcal{P}^3_m,\mathcal{C}^3_n)=2n+\lfloor\frac{m-1}{2}\rfloor. These give a positive answer to a question of Gy\'{a}rf\'{a}s and Raeisi [The Ramsey number of loose triangles and quadrangles in hypergraphs, Electron. J. Combin. 19 (2012), #R30].

Keywords

Cite

@article{arxiv.1211.5800,
  title  = {Ramsey numbers of 3-uniform loose paths and loose cycles},
  author = {Gholamreza Omidi and Maryam Shahsiah},
  journal= {arXiv preprint arXiv:1211.5800},
  year   = {2012}
}