English

Ramsey numbers for complete graphs versus generalized fans

Combinatorics 2021-11-12 v1

Abstract

For two graphs GG and HH, let r(G,H)r(G,H) and r(G,H)r_*(G,H) denote the Ramsey number and star-critical Ramsey number of GG versus HH, respectively. In 1996, Li and Rousseau proved that r(Km,Ft,n)=tn(m1)+1r(K_{m},F_{t,n})=tn(m-1)+1 for m3m\geq 3 and sufficiently large nn, where Ft,n=K1+nKtF_{t,n}=K_{1}+nK_{t}. Recently, Hao and Lin proved that r(K3,F3,n)=6n+1r(K_{3},F_{3,n})=6n+1 for n3n\geq 3 and r(K3,F3,n)=3n+3r_{\ast}(K_{3},F_{3,n})=3n+3 for n4n\geq 4. In this paper, we show that r(Km,sFt,n)=tn(m+s2)+sr(K_{m}, sF_{t,n})=tn(m+s-2)+s for sufficiently large nn and, in particular, r(K3,sFt,n)=tn(s+1)+sr(K_{3}, sF_{t,n})=tn(s+1)+s for t{3,4},ntt\in\{3,4\},n\geq t and s1s\geq1. We also show that r(K3,F4,n)=4n+4r_{\ast}(K_{3}, F_{4,n})=4n+4 for n4n\geq 4 and establish an upper bound on r(F2,m,Ft,n)r(F_{2,m},F_{t,n}).

Keywords

Cite

@article{arxiv.2111.06107,
  title  = {Ramsey numbers for complete graphs versus generalized fans},
  author = {Maoqun Wang and Jianguo Qian},
  journal= {arXiv preprint arXiv:2111.06107},
  year   = {2021}
}

Comments

9 pages

R2 v1 2026-06-24T07:34:47.996Z