3-Factor-criticality in double domination edge critical graphs

TL;DR

This paper investigates the properties of 3-factor-critical graphs within the class of 3-connected, claw-free, double domination edge critical graphs of odd order, establishing conditions under which such graphs are 3-factor-critical.

Contribution

It characterizes when certain double domination edge critical graphs are 3-factor-critical, extending understanding of their structural properties.

Findings

G is 3-factor-critical under specified conditions.

Identifies exceptions within the class of graphs studied.

Provides a characterization linking connectivity, claw-freeness, and criticality.

Abstract

A vertex subset $S$ of a graph $G$ is a double dominating set of $G$ if $|N[v]\cap S|\geq 2$ for each vertex $v$ of $G$, where $N[v]$ is the set of the vertex $v$ and vertices adjacent to $v$. The double domination number of $G$, denoted by $\gamma_{\times 2}(G)$, is the cardinality of a smallest double dominating set of $G$. A graph $G$ is said to be double domination edge critical if $\gamma_{\times 2}(G+e)<\gamma_{\times 2}(G)$ for any edge $e \notin E$. A double domination edge critical graph $G$ with $\gamma_{\times 2}(G)=k$ is called $k$-$\gamma_{\times 2}(G)$-critical. A graph $G$ is $r$-factor-critical if $G-S$ has a perfect matching for each set $S$ of $r$ vertices in $G$. In this paper we show that $G$ is 3-factor-critical if $G$ is a 3-connected claw-free $4$-$\gamma_{\times 2}(G)$-critical graph of odd order with minimum degree at least 4 except a family of graphs.