A Fan-type condition involving bipartite independence number for hamiltonicity in graphs

Fuente: arXiv
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Main Authors: Liu, Hongxi, Yuan, Long-Tu, Zhang, Xiaowen
Format: Preprint
Published: 2025
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author Liu, Hongxi
Yuan, Long-Tu
Zhang, Xiaowen
author_facet Liu, Hongxi
Yuan, Long-Tu
Zhang, Xiaowen
contents The bipartite independence number of a graph $G$, denoted by $\widetildeα(G)$, is defined as the smallest integer $q$ for which there exist positive integers $s$ and $t$ with $s + t = q + 1$, such that for any two disjoint subsets $A, B \subseteq V(G)$ with $|A| = s$ and $|B| = t$, there exists an edge between $A$ and $B$. In this paper, we prove that for a 2-connected graph $G$ of order at least three, if $\max\{d_G(x), d_G(y)\} \ge \widetildeα(G)$ for every pair of nonadjacent vertices $x, y$ at distance two, then $G$ is hamiltonian. Moreover, we prove that if $G$ is 3-connected and $\max\{d_G(x), d_G(y)\} \ge \widetildeα(G)+1$ for every pair of nonadjacent vertices $x, y$ at distance two, then $G$ is hamiltonian-connected. Our results generalize the recent work by Li and Liu.
format Preprint
id arxiv_https___arxiv_org_abs_2506_02687
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle A Fan-type condition involving bipartite independence number for hamiltonicity in graphs
Liu, Hongxi
Yuan, Long-Tu
Zhang, Xiaowen
Combinatorics
05C45, 05C38
The bipartite independence number of a graph $G$, denoted by $\widetildeα(G)$, is defined as the smallest integer $q$ for which there exist positive integers $s$ and $t$ with $s + t = q + 1$, such that for any two disjoint subsets $A, B \subseteq V(G)$ with $|A| = s$ and $|B| = t$, there exists an edge between $A$ and $B$. In this paper, we prove that for a 2-connected graph $G$ of order at least three, if $\max\{d_G(x), d_G(y)\} \ge \widetildeα(G)$ for every pair of nonadjacent vertices $x, y$ at distance two, then $G$ is hamiltonian. Moreover, we prove that if $G$ is 3-connected and $\max\{d_G(x), d_G(y)\} \ge \widetildeα(G)+1$ for every pair of nonadjacent vertices $x, y$ at distance two, then $G$ is hamiltonian-connected. Our results generalize the recent work by Li and Liu.
title A Fan-type condition involving bipartite independence number for hamiltonicity in graphs
topic Combinatorics
05C45, 05C38
url https://arxiv.org/abs/2506.02687