Cubic graphs with edges in exactly one perfect matching

Fuente: arXiv
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Autori principali: Goedgebeur, Jan, Mattiolo, Davide, Mazzuoccolo, Giuseppe, Renders, Jarne, Wolf, Isaak H.
Natura: Preprint
Pubblicazione: 2024
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author Goedgebeur, Jan
Mattiolo, Davide
Mazzuoccolo, Giuseppe
Renders, Jarne
Wolf, Isaak H.
author_facet Goedgebeur, Jan
Mattiolo, Davide
Mazzuoccolo, Giuseppe
Renders, Jarne
Wolf, Isaak H.
contents Petersen's seminal work in 1891 asserts that the edge-set of a cubic graph can be covered by distinct perfect matchings if and only if it is bridgeless. Actually, it is known that for a very large fraction of bridgeless cubic graphs, every edge belongs to at least two distinct perfect matchings. In this paper, we study the class of non-double covered cubic graphs, i.e.\ graphs having an edge, called lonely edge, which belongs to exactly one perfect matching. First of all, we provide a reduction of the problem to the subclass $\cal U$ of $3$-connected cubic graphs. Then, we furnish an inductive characterization of $\cal U$ and we study properties related to the count of lonely edges. In particular, denoting by $\mathcal{U}_k$ the subclass of graphs of $\cal U$ with exactly $k$ lonely edges, we prove that $\mathcal{U}_k$ is empty for $k>6$, and we present a complete characterization for $3 \leq k \leq 6$. The paper concludes with some insights on ${\cal U}_1$ and ${\cal U}_2$.
format Preprint
id arxiv_https___arxiv_org_abs_2402_08538
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Cubic graphs with edges in exactly one perfect matching
Goedgebeur, Jan
Mattiolo, Davide
Mazzuoccolo, Giuseppe
Renders, Jarne
Wolf, Isaak H.
Combinatorics
05C75
Petersen's seminal work in 1891 asserts that the edge-set of a cubic graph can be covered by distinct perfect matchings if and only if it is bridgeless. Actually, it is known that for a very large fraction of bridgeless cubic graphs, every edge belongs to at least two distinct perfect matchings. In this paper, we study the class of non-double covered cubic graphs, i.e.\ graphs having an edge, called lonely edge, which belongs to exactly one perfect matching. First of all, we provide a reduction of the problem to the subclass $\cal U$ of $3$-connected cubic graphs. Then, we furnish an inductive characterization of $\cal U$ and we study properties related to the count of lonely edges. In particular, denoting by $\mathcal{U}_k$ the subclass of graphs of $\cal U$ with exactly $k$ lonely edges, we prove that $\mathcal{U}_k$ is empty for $k>6$, and we present a complete characterization for $3 \leq k \leq 6$. The paper concludes with some insights on ${\cal U}_1$ and ${\cal U}_2$.
title Cubic graphs with edges in exactly one perfect matching
topic Combinatorics
05C75
url https://arxiv.org/abs/2402.08538