Augmenting a hypergraph to have a matroid-based $(f,g)$-bounded $(α,β)$-limited packing of rooted hypertrees

Fuente: arXiv
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Autores principales: Hoppenot, Pierre, Szigeti, Zoltán
Formato: Preprint
Publicado: 2024
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author Hoppenot, Pierre
Szigeti, Zoltán
author_facet Hoppenot, Pierre
Szigeti, Zoltán
contents The aim of this paper is to further develop the theory of packing trees in a graph. We first prove the classic result of Nash-Williams \cite{NW} and Tutte \cite{Tu} on packing spanning trees by adapting Lovász' proof \cite{Lov} of the seminal result of Edmonds \cite{Egy} on packing spanning arborescences in a digraph. Our main result on graphs extends the theorem of Katoh and Tanigawa \cite{KT} on matroid-based packing of rooted trees by characterizing the existence of such a packing satisfying the following further conditions: for every vertex $v$, there are a lower bound $f(v)$ and an upper bound $g(v)$ on the number of trees rooted at $v$ and there are a lower bound $α$ and an upper bound $β$ on the total number of roots. We also answer the hypergraphic version of the problem. Furthermore, we are able to solve the augmentation version of the latter problem, where the goal is to add a minimum number of edges to have such a packing. The methods developed in this paper to solve these problems may have other applications in the future.
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id arxiv_https___arxiv_org_abs_2412_03363
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Augmenting a hypergraph to have a matroid-based $(f,g)$-bounded $(α,β)$-limited packing of rooted hypertrees
Hoppenot, Pierre
Szigeti, Zoltán
Combinatorics
Discrete Mathematics
The aim of this paper is to further develop the theory of packing trees in a graph. We first prove the classic result of Nash-Williams \cite{NW} and Tutte \cite{Tu} on packing spanning trees by adapting Lovász' proof \cite{Lov} of the seminal result of Edmonds \cite{Egy} on packing spanning arborescences in a digraph. Our main result on graphs extends the theorem of Katoh and Tanigawa \cite{KT} on matroid-based packing of rooted trees by characterizing the existence of such a packing satisfying the following further conditions: for every vertex $v$, there are a lower bound $f(v)$ and an upper bound $g(v)$ on the number of trees rooted at $v$ and there are a lower bound $α$ and an upper bound $β$ on the total number of roots. We also answer the hypergraphic version of the problem. Furthermore, we are able to solve the augmentation version of the latter problem, where the goal is to add a minimum number of edges to have such a packing. The methods developed in this paper to solve these problems may have other applications in the future.
title Augmenting a hypergraph to have a matroid-based $(f,g)$-bounded $(α,β)$-limited packing of rooted hypertrees
topic Combinatorics
Discrete Mathematics
url https://arxiv.org/abs/2412.03363