English

An exact Ramsey number of large bipartite graphs versus odd wheel

Combinatorics 2026-01-19 v2

Abstract

The Ramsey number for the pair of graphs K1,n\mathbb{K}_{1,n} (star) versus WmW_{m} (wheel) has been extensively studied. In contrast, the Ramsey number of K2,n\mathbb{K}_{2,n} versus the wheel is not yet explored due to the bit more structural complexity of K2,n\mathbb{K}_{2,n} compared to the star. In this article, we have established an exact value of K2,n\mathbb{K}_{2,n} versus WmW_{m} for large nn and mm. In particular, we have proved \begin{equation*} R(\mathbb{K}_{2,n}, W_{m})=3n+4, \end{equation*} whenever nn and mm are sufficiently large integers satisfying n4mn\geq4m and mm is an odd integer. This proves the WmW_{m}-goodness of K2,n\mathbb{K}_{2,n}. Our proof combines probabilistic methods with an analysis of structural dependencies. As part of the argument, we resolve a structural rigidity question concerning highly dependent neighbourhoods (Lemma 3.12).

Keywords

Cite

@article{arxiv.2511.14867,
  title  = {An exact Ramsey number of large bipartite graphs versus odd wheel},
  author = {Sayan Gupta and Kaushik Majumder},
  journal= {arXiv preprint arXiv:2511.14867},
  year   = {2026}
}

Comments

Ramsey Numbers, Ramsey Goodness, Wheel, 2-connectedness