English

A sharp Ore-type condition for a connected graph with no induced star to have a Hamiltonian path

Combinatorics 2020-01-07 v2

Abstract

We say a graph GG has a Hamiltonian path if it has a path containing all vertices of GG. For a graph GG, let σ2(G)\sigma_2(G) denote the minimum degree sum of two nonadjacent vertices of GG; restrictions on σ2(G)\sigma_2(G) are known as Ore-type conditions. Given an integer t5t\geq 5, we prove that if a connected graph GG on nn vertices satisfies σ2(G)>t3t2n\sigma_2(G)>{t-3\over t-2}n, then GG has either a Hamiltonian path or an induced subgraph isomorphic to K1,tK_{1, t}. Moreover, we characterize all nn-vertex graphs GG where σ2(G)=t3t2n\sigma_2(G)={t-3\over t-2}n and GG has neither a Hamiltonian path nor an induced subgraph isomorphic to K1,tK_{1, t}. This is an analogue of a recent result by Mom\`ege, who investigated the case when t=4t=4.

Keywords

Cite

@article{arxiv.2001.00385,
  title  = {A sharp Ore-type condition for a connected graph with no induced star to have a Hamiltonian path},
  author = {Ilkyoo Choi and Jinha Kim},
  journal= {arXiv preprint arXiv:2001.00385},
  year   = {2020}
}
R2 v1 2026-06-23T13:01:14.770Z