English

Size Ramsey numbers of stars versus cliques

Combinatorics 2016-09-14 v2

Abstract

The size Ramsey number r^(G,H) \hat{r}(G,H) of two graphs G G and H H is the smallest integer m m such that there exists a graph F F on m m edges with the property that every red-blue colouring of the edges of F F , yields a red copy of G G or a blue copy of H H . In 1981 1981 , Erd\H{o}s observed that r^(K1,k,K3)(2k+12)(k2)\hat{r}(K_{1,k},K_{3})\leq \binom{2k+1}{2}-\binom{k}{2} and he conjectured that the corresponding upper bound on r^(K1,k,K3) \hat{r}(K_{1,k},K_{3}) is sharp. In 1983 1983 , Faudree and Sheehan extended this conjecture as follows: \hat{r}(K_{1,k},K_{n})=\left \{ {lr} \binom{k(n-1)+1}{2}-\binom{k}{2} & ~k\geq n~ \text{or}~ k~ \text{odd}. \binom{k(n-1)+1}{2}-k(n-1)/2 & \text{otherwise}. \right. They proved the case k=2 k=2 . In 2001 2001 , Pikhurko showed that this conjecture is not true for n=3 n=3 and k5 k\geq 5 , disproving the mentioned conjecture of Erd\H{o}s. Here we prove Faudree and Sheehan's conjecture for a given k2 k\geq 2 and nk3+2k2+2k n\geq k^{3}+2k^{2}+2k .

Keywords

Cite

@article{arxiv.1601.06599,
  title  = {Size Ramsey numbers of stars versus cliques},
  author = {Meysam Miralaei and Gholamreza Omidi and Maryam Shahsiah},
  journal= {arXiv preprint arXiv:1601.06599},
  year   = {2016}
}