Counting Small Cycle Double Covers

Fuente: arXiv
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Main Authors: Jooken, Jorik, Seamone, Ben, Zamfirescu, Carol T.
Format: Preprint
Published: 2025
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_version_ 1866908405781757952
author Jooken, Jorik
Seamone, Ben
Zamfirescu, Carol T.
author_facet Jooken, Jorik
Seamone, Ben
Zamfirescu, Carol T.
contents A theorem due to Seyffarth states that every planar $4$-connected $n$-vertex graph has a cycle double cover (CDC) containing at most $n-1$ cycles (a "small" CDC). We extend this theorem by proving that, in fact, such a graph must contain linearly many small CDCs (in terms of $n$), and provide stronger results in the case of planar $4$-connected triangulations. We complement this result with constructions of planar $4$-connected graphs which contain at most polynomially many small CDCs. Thereafter we treat cubic graphs, strengthening a lemma of Hušek and Šámal on the enumeration of CDCs, and, motivated by a conjecture of Bondy, give an alternative proof of the result that every planar 2-connected cubic graph on $n > 4$ vertices has a CDC of size at most $n/2$. Our proof is much shorter and obtained by combining a decomposition based argument, which might be of independent interest, with further combinatorial insights. Some of our results are accompanied by a version thereof for CDCs containing no cycle twice.
format Preprint
id arxiv_https___arxiv_org_abs_2506_10604
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Counting Small Cycle Double Covers
Jooken, Jorik
Seamone, Ben
Zamfirescu, Carol T.
Combinatorics
05C38, 05C45, 05C10, 05C30
A theorem due to Seyffarth states that every planar $4$-connected $n$-vertex graph has a cycle double cover (CDC) containing at most $n-1$ cycles (a "small" CDC). We extend this theorem by proving that, in fact, such a graph must contain linearly many small CDCs (in terms of $n$), and provide stronger results in the case of planar $4$-connected triangulations. We complement this result with constructions of planar $4$-connected graphs which contain at most polynomially many small CDCs. Thereafter we treat cubic graphs, strengthening a lemma of Hušek and Šámal on the enumeration of CDCs, and, motivated by a conjecture of Bondy, give an alternative proof of the result that every planar 2-connected cubic graph on $n > 4$ vertices has a CDC of size at most $n/2$. Our proof is much shorter and obtained by combining a decomposition based argument, which might be of independent interest, with further combinatorial insights. Some of our results are accompanied by a version thereof for CDCs containing no cycle twice.
title Counting Small Cycle Double Covers
topic Combinatorics
05C38, 05C45, 05C10, 05C30
url https://arxiv.org/abs/2506.10604