A Tutte-type canonical decomposition of 3- and 4-connected graphs

Fuente: arXiv
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Main Authors: Kurkofka, Jan, Planken, Tim
Format: Preprint
Published: 2025
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author Kurkofka, Jan
Planken, Tim
author_facet Kurkofka, Jan
Planken, Tim
contents We provide a unique decomposition of every 4-connected graph into parts that are either quasi-5-connected, cycles of triangle-torsos and 3-connected torsos on $\leq 5$ vertices, generalised double-wheels, or thickened $K_{4,m}$'s. The decomposition can be described in terms of a tree-decomposition but with edges allowed in the adhesion-sets. Our construction is explicit, canonical, and exhibits a defining property of the Tutte-decomposition. As a corollary, we obtain a new Tutte-type canonical decomposition of 3-connected graphs into parts that are either quasi-4-connected, generalised wheels or thickened $K_{3,m}$'s. This decomposition is similar yet different from the tri-separation decomposition. As an application of the decomposition for 4-connectivity, in a follow-up paper we obtain a new theorem characterising all vertex-transitive finite connected graphs as essentially quasi-5-connected or on a short explicit list of graphs.
format Preprint
id arxiv_https___arxiv_org_abs_2504_00760
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle A Tutte-type canonical decomposition of 3- and 4-connected graphs
Kurkofka, Jan
Planken, Tim
Combinatorics
Discrete Mathematics
05C40 (Primary) 05C75, 05C83, 05E18 (Secondary)
We provide a unique decomposition of every 4-connected graph into parts that are either quasi-5-connected, cycles of triangle-torsos and 3-connected torsos on $\leq 5$ vertices, generalised double-wheels, or thickened $K_{4,m}$'s. The decomposition can be described in terms of a tree-decomposition but with edges allowed in the adhesion-sets. Our construction is explicit, canonical, and exhibits a defining property of the Tutte-decomposition. As a corollary, we obtain a new Tutte-type canonical decomposition of 3-connected graphs into parts that are either quasi-4-connected, generalised wheels or thickened $K_{3,m}$'s. This decomposition is similar yet different from the tri-separation decomposition. As an application of the decomposition for 4-connectivity, in a follow-up paper we obtain a new theorem characterising all vertex-transitive finite connected graphs as essentially quasi-5-connected or on a short explicit list of graphs.
title A Tutte-type canonical decomposition of 3- and 4-connected graphs
topic Combinatorics
Discrete Mathematics
05C40 (Primary) 05C75, 05C83, 05E18 (Secondary)
url https://arxiv.org/abs/2504.00760