Splitting-off in Hypergraphs

Fuente: arXiv
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Main Authors: Bérczi, Kristóf, Chandrasekaran, Karthekeyan, Király, Tamás, Kulkarni, Shubhang
Format: Preprint
Published: 2023
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author Bérczi, Kristóf
Chandrasekaran, Karthekeyan
Király, Tamás
Kulkarni, Shubhang
author_facet Bérczi, Kristóf
Chandrasekaran, Karthekeyan
Király, Tamás
Kulkarni, Shubhang
contents The splitting-off operation in undirected graphs is a fundamental reduction operation that detaches all edges incident to a given vertex and adds new edges between the neighbors of that vertex while preserving their degrees. Lovász (1974) and Mader (1978) showed the existence of this operation while preserving global and local connectivities respectively in graphs under certain conditions. These results have far-reaching applications in graph algorithms literature. In this work, we introduce a splitting-off operation in hypergraphs. We show that there exists a local connectivity preserving complete splitting-off in hypergraphs and give a strongly polynomial-time algorithm to compute it in weighted hypergraphs. We illustrate the usefulness of our splitting-off operation in hypergraphs by showing two applications: (1) we give a constructive characterization of $k$-hyperedge-connected hypergraphs and (2) we give an alternate proof of an approximate min-max relation for max Steiner rooted-connected orientation of graphs and hypergraphs (due to Király and Lau (Journal of Combinatorial Theory, 2008; FOCS 2006)). Our proof of the approximate min-max relation for graphs circumvents the Nash-Williams' strong orientation theorem and uses tools developed for hypergraphs.
format Preprint
id arxiv_https___arxiv_org_abs_2307_08555
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle Splitting-off in Hypergraphs
Bérczi, Kristóf
Chandrasekaran, Karthekeyan
Király, Tamás
Kulkarni, Shubhang
Data Structures and Algorithms
Discrete Mathematics
The splitting-off operation in undirected graphs is a fundamental reduction operation that detaches all edges incident to a given vertex and adds new edges between the neighbors of that vertex while preserving their degrees. Lovász (1974) and Mader (1978) showed the existence of this operation while preserving global and local connectivities respectively in graphs under certain conditions. These results have far-reaching applications in graph algorithms literature. In this work, we introduce a splitting-off operation in hypergraphs. We show that there exists a local connectivity preserving complete splitting-off in hypergraphs and give a strongly polynomial-time algorithm to compute it in weighted hypergraphs. We illustrate the usefulness of our splitting-off operation in hypergraphs by showing two applications: (1) we give a constructive characterization of $k$-hyperedge-connected hypergraphs and (2) we give an alternate proof of an approximate min-max relation for max Steiner rooted-connected orientation of graphs and hypergraphs (due to Király and Lau (Journal of Combinatorial Theory, 2008; FOCS 2006)). Our proof of the approximate min-max relation for graphs circumvents the Nash-Williams' strong orientation theorem and uses tools developed for hypergraphs.
title Splitting-off in Hypergraphs
topic Data Structures and Algorithms
Discrete Mathematics
url https://arxiv.org/abs/2307.08555