English

Ramsey goodness of complete multipartite graphs with one large part

Combinatorics 2026-05-27 v1

Abstract

For graph GG, a connected graph HH of order nn is said to be GG-good if r(G,H)=(χ(G)1)(n1)+s(G)r(G,H)=(\chi(G)-1)(n-1)+s(G), where χ(G)\chi(G) is the chromatic number of GG and s(G)s(G) is the minimum size of a color class in a χ(G)\chi(G)-coloring of GG. Let Kp+1(α;n)K_{p+1}(\alpha;n) denote the complete (p+1)(p+1)-partite graph with pp partite sets of size α\alpha and one partite set of size nn. We determine all graphs GG for which Kp+1(α;n)K_{p+1}(\alpha;n) is GG-good for large nn. The characterization depends on the parameter snd(α)\mathrm{snd}(\alpha), the smallest non-divisor of α\alpha.

Keywords

Cite

@article{arxiv.2605.26826,
  title  = {Ramsey goodness of complete multipartite graphs with one large part},
  author = {Shaonan Mi and Ye Wang},
  journal= {arXiv preprint arXiv:2605.26826},
  year   = {2026}
}