English

The size-Ramsey number of short subdivisions

Combinatorics 2020-11-12 v2

Abstract

The rr-size-Ramsey number R^r(H)\hat{R}_r(H) of a graph HH is the smallest number of edges a graph GG can have, such that for every edge-coloring of GG with rr colors there exists a monochromatic copy of HH in GG. For a graph HH, we denote by HqH^q the graph obtained from HH by subdividing its edges with q1q{-}1 vertices each. In a recent paper of Kohayakawa, Retter and R{\"o}dl, it is shown that for all constant integers q,r2q,r\geq 2 and every graph HH on nn vertices and of bounded maximum degree, the rr-size-Ramsey number of HqH^q is at most (logn)20(q1)n1+1/q(\log n)^{20(q-1)}n^{1+1/q}, for nn large enough. We improve upon this result using a significantly shorter argument by showing that R^r(Hq)O(n1+1/q)\hat{R}_r(H^q)\leq O(n^{1+1/q}) for any such graph HH.

Keywords

Cite

@article{arxiv.2004.14139,
  title  = {The size-Ramsey number of short subdivisions},
  author = {Nemanja Draganić and Michael Krivelevich and Rajko Nenadov},
  journal= {arXiv preprint arXiv:2004.14139},
  year   = {2020}
}

Comments

12 pages, 1 figure