Classification and Construction of Planar, 3-Connected Kronecker Products

Fuente: arXiv
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Main Author: Maffucci, Riccardo W.
Format: Preprint
Published: 2024
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author Maffucci, Riccardo W.
author_facet Maffucci, Riccardo W.
contents We give a complete classification of the Kronecker (i.e. direct) product graphs that are planar and $3$-connected (i.e. $3$-polytopal). They are all of the form \[H\wedge K_2,\] where $H$ is a $2$-connected graph, possibly non-planar, and satisfying specific properties that we will describe. Our proof is constructive, in the sense that we prescribe how to obtain all such graphs $H$, by adding a few edges in a specific way to a given planar, bipartite graph, that is either $3$-connected, or semi-hyper-$2$-connected. Moreover, for $H$ planar, we also give a more precise characterisation of this graph, regarding the number of its odd regions, and how they intersect. If $H\wedge K_2$ is a $3$-polytope, then we have $δ(H\wedge K_2)=3$, so that the connectivity of $H\wedge K_2$ is $3$, and the connectivity of $H$ is either $2$ or $3$. We also briefly discuss which Cartesian and strong products are $3$-polytopal.
format Preprint
id arxiv_https___arxiv_org_abs_2402_01407
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Classification and Construction of Planar, 3-Connected Kronecker Products
Maffucci, Riccardo W.
Combinatorics
05C75, 05C76, 05C62, 05C10, 05C40, 52B05, 52B10, 05C85, 05C83
We give a complete classification of the Kronecker (i.e. direct) product graphs that are planar and $3$-connected (i.e. $3$-polytopal). They are all of the form \[H\wedge K_2,\] where $H$ is a $2$-connected graph, possibly non-planar, and satisfying specific properties that we will describe. Our proof is constructive, in the sense that we prescribe how to obtain all such graphs $H$, by adding a few edges in a specific way to a given planar, bipartite graph, that is either $3$-connected, or semi-hyper-$2$-connected. Moreover, for $H$ planar, we also give a more precise characterisation of this graph, regarding the number of its odd regions, and how they intersect. If $H\wedge K_2$ is a $3$-polytope, then we have $δ(H\wedge K_2)=3$, so that the connectivity of $H\wedge K_2$ is $3$, and the connectivity of $H$ is either $2$ or $3$. We also briefly discuss which Cartesian and strong products are $3$-polytopal.
title Classification and Construction of Planar, 3-Connected Kronecker Products
topic Combinatorics
05C75, 05C76, 05C62, 05C10, 05C40, 52B05, 52B10, 05C85, 05C83
url https://arxiv.org/abs/2402.01407