Some sufficient conditions for path-factor uniform graphs

TL;DR

This paper establishes sufficient conditions involving connectivity and degree constraints under which graphs are guaranteed to have a path-factor uniform property, ensuring coverage of any two edges with specific path factors.

Contribution

It provides new criteria for 2-edge-connected and highly connected graphs to be $P_{ extgreater{}d}$-factor uniform, extending understanding of path-factor properties in graph theory.

Findings

A 2-edge-connected graph with certain degree conditions is $P_{ extgreater{}3}$-factor uniform.

Highly connected graphs with specified neighborhood conditions are $P_{ extgreater{}3}$-factor uniform.

The paper offers explicit bounds and conditions linking connectivity, independence, and neighborhood size to path-factor uniformity.

Abstract

For a set $\mathcal{H}$ of connected graphs, a spanning subgraph $H$ of $G$ is called an $\mathcal{H}$-factor of $G$ if each component of $H$ is isomorphic to an element of $\mathcal{H}$. A graph $G$ is called an $\mathcal{H}$-factor uniform graph if for any two edges $e_1$ and $e_2$ of $G$, $G$ has an $\mathcal{H}$-factor covering $e_1$ and excluding $e_2$. Let each component in $\mathcal{H}$ be a path with at least $d$ vertices, where $d\geq2$ is an integer. Then an $\mathcal{H}$-factor and an $\mathcal{H}$-factor uniform graph are called a $P_{\geq d}$-factor and a $P_{\geq d}$-factor uniform graph, respectively. In this article, we verify that (\romannumeral1) a 2-edge-connected graph $G$ is a $P_{\geq3}$-factor uniform graph if $\delta(G)>\frac{\alpha(G)+4}{2}$; (\romannumeral2) a $(k+2)$-connected graph $G$ of order $n$ with $n\geq5k+3-\frac{3}{5\gamma-1}$ is a $P_{\geq3}$-factor uniform graph if $|N_G(A)|>\gamma(n-3k-2)+k+2$ for any independent set $A$ of $G$ with $|A|=\lfloor\gamma(2k+1)\rfloor$, where $k$ is a positive integer and $\gamma$ is a real number with $\frac{1}{3}\leq\gamma\leq1$.