Approximating maximum-size properly colored forests

Fuente: arXiv
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Auteurs principaux: Bai, Yuhang, Bérczi, Kristóf, Csáji, Gergely, Schwarcz, Tamás
Format: Preprint
Publié: 2024
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author Bai, Yuhang
Bérczi, Kristóf
Csáji, Gergely
Schwarcz, Tamás
author_facet Bai, Yuhang
Bérczi, Kristóf
Csáji, Gergely
Schwarcz, Tamás
contents In the Properly Colored Spanning Tree problem, we are given an edge-colored undirected graph and the goal is to find a properly colored spanning tree, i.e., a spanning tree in which any two adjacent edges have distinct colors. The problem is interesting not only from a graph coloring point of view, but is also closely related to the Degree Bounded Spanning Tree and (1,2)-Traveling Salesman problems, two classical questions that have attracted considerable interest in combinatorial optimization and approximation theory. Previous work on properly colored spanning trees has mainly focused on determining the existence of such a tree and hence has not considered the question from an algorithmic perspective. We propose an optimization version called Maximum-size Properly Colored Forest problem, which aims to find a properly colored forest with as many edges as possible. We consider the problem in different graph classes and for different numbers of colors, and present polynomial-time approximation algorithms as well as inapproximability results for these settings. Our proof technique relies on the sum of matching matroids defined by the color classes, a connection that might be of independent combinatorial interest. We also consider the Maximum-size Properly Colored Tree problem, which asks for the maximum size of a properly colored tree not necessarily spanning all the vertices. We show that the optimum is significantly more difficult to approximate than in the forest case, and provide an approximation algorithm for complete multigraphs.
format Preprint
id arxiv_https___arxiv_org_abs_2402_00834
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Approximating maximum-size properly colored forests
Bai, Yuhang
Bérczi, Kristóf
Csáji, Gergely
Schwarcz, Tamás
Data Structures and Algorithms
Discrete Mathematics
Combinatorics
In the Properly Colored Spanning Tree problem, we are given an edge-colored undirected graph and the goal is to find a properly colored spanning tree, i.e., a spanning tree in which any two adjacent edges have distinct colors. The problem is interesting not only from a graph coloring point of view, but is also closely related to the Degree Bounded Spanning Tree and (1,2)-Traveling Salesman problems, two classical questions that have attracted considerable interest in combinatorial optimization and approximation theory. Previous work on properly colored spanning trees has mainly focused on determining the existence of such a tree and hence has not considered the question from an algorithmic perspective. We propose an optimization version called Maximum-size Properly Colored Forest problem, which aims to find a properly colored forest with as many edges as possible. We consider the problem in different graph classes and for different numbers of colors, and present polynomial-time approximation algorithms as well as inapproximability results for these settings. Our proof technique relies on the sum of matching matroids defined by the color classes, a connection that might be of independent combinatorial interest. We also consider the Maximum-size Properly Colored Tree problem, which asks for the maximum size of a properly colored tree not necessarily spanning all the vertices. We show that the optimum is significantly more difficult to approximate than in the forest case, and provide an approximation algorithm for complete multigraphs.
title Approximating maximum-size properly colored forests
topic Data Structures and Algorithms
Discrete Mathematics
Combinatorics
url https://arxiv.org/abs/2402.00834