English

Diagonal Ramsey numbers for wheels

Combinatorics 2026-05-22 v1

Abstract

The Ramsey number R(G1,G2)\mathrm{R}(G_1,G_2) is the smallest integer NN such that any red-blue coloring of the edges of the complete graph KNK_N contains either a red copy of G1G_1 or a blue copy of G2G_2. In 2022, the third author and others gave lower and upper bounds of the Ramsey number R(Wn,Wn)\mathrm{R}(W_n,W_n), where WnW_n is the wheel graph with nn vertices. In this paper, we improve their bounds by showing that 3n2R(Wn,Wn)6n63n-2\leq \mathrm{R}(W_n,W_n)\leq 6n-6 for even n8n\geq 8 and 2nR(Wn,Wn)9n722n\leq \mathrm{R}(W_n,W_n)\leq \frac{9n-7}{2} for odd n7n\geq 7. Furthermore, we give recursive bounds for the kk-colored Ramsey number for WnW_n.

Keywords

Cite

@article{arxiv.2605.22116,
  title  = {Diagonal Ramsey numbers for wheels},
  author = {Maoxuan Li and Masaki Kashima and Yaping Mao},
  journal= {arXiv preprint arXiv:2605.22116},
  year   = {2026}
}