Bounded indegree $k$-forests problem and a faster algorithm for directed graph augmentation

Fuente: arXiv
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Main Authors: Arkhipov, Pavel, Kolmogorov, Vladimir
Format: Preprint
Published: 2024
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author Arkhipov, Pavel
Kolmogorov, Vladimir
author_facet Arkhipov, Pavel
Kolmogorov, Vladimir
contents We consider two problems for a directed graph $G$, which we show to be closely related. The first one is to find $k$ edge-disjoint forests in $G$ of maximal size such that the indegree of each vertex in these forests is at most $k$. We describe a min-max characterization for this problem and show that it can be solved in $O(k δm \log n)$ time, where $(n,m)$ is the size of $G$ and $δ$ is the difference between $k$ and the edge connectivity of the graph. The second problem is the directed edge-connectivity augmentation problem, which has been extensively studied before: find a smallest set of directed edges whose addition to the graph makes it strongly $k$-connected. We improve the complexity for this problem from $O(k δ(m+δn)\log n)$ [Gabow, STOC 1994] to $O(k δm \log n)$, by exploiting our solution for the first problem. A similar approach with the same complexity also works for the undirected version of the problem.
format Preprint
id arxiv_https___arxiv_org_abs_2409_14881
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Bounded indegree $k$-forests problem and a faster algorithm for directed graph augmentation
Arkhipov, Pavel
Kolmogorov, Vladimir
Data Structures and Algorithms
Discrete Mathematics
Combinatorics
We consider two problems for a directed graph $G$, which we show to be closely related. The first one is to find $k$ edge-disjoint forests in $G$ of maximal size such that the indegree of each vertex in these forests is at most $k$. We describe a min-max characterization for this problem and show that it can be solved in $O(k δm \log n)$ time, where $(n,m)$ is the size of $G$ and $δ$ is the difference between $k$ and the edge connectivity of the graph. The second problem is the directed edge-connectivity augmentation problem, which has been extensively studied before: find a smallest set of directed edges whose addition to the graph makes it strongly $k$-connected. We improve the complexity for this problem from $O(k δ(m+δn)\log n)$ [Gabow, STOC 1994] to $O(k δm \log n)$, by exploiting our solution for the first problem. A similar approach with the same complexity also works for the undirected version of the problem.
title Bounded indegree $k$-forests problem and a faster algorithm for directed graph augmentation
topic Data Structures and Algorithms
Discrete Mathematics
Combinatorics
url https://arxiv.org/abs/2409.14881