The Simultaneous Interval Number: A New Width Parameter that Measures the Similarity to Interval Graphs

Fuente: arXiv
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Main Authors: Beisegel, Jesse, Chiarelli, Nina, Köhler, Ekkehard, Milanič, Martin, Muršič, Peter, Scheffler, Robert
Format: Preprint
Published: 2024
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author Beisegel, Jesse
Chiarelli, Nina
Köhler, Ekkehard
Milanič, Martin
Muršič, Peter
Scheffler, Robert
author_facet Beisegel, Jesse
Chiarelli, Nina
Köhler, Ekkehard
Milanič, Martin
Muršič, Peter
Scheffler, Robert
contents We propose a novel way of generalizing the class of interval graphs, via a graph width parameter called the simultaneous interval number. This parameter is related to the simultaneous representation problem for interval graphs and defined as the smallest number $d$ of labels such that the graph admits a $d$-simultaneous interval representation, that is, an assignment of intervals and label sets to the vertices such that two vertices are adjacent if and only if the corresponding intervals, as well as their label sets, intersect. We show that this parameter is $\mathsf{NP}$-hard to compute and give several bounds for the parameter, showing in particular that it is sandwiched between pathwidth and linear mim-width. For classes of graphs with bounded parameter values, assuming that the graph is equipped with a simultaneous interval representation with a constant number of labels, we give $\mathsf{FPT}$ algorithms for the clique, independent set, and dominating set problems, and hardness results for the independent dominating set and coloring problems. The $\mathsf{FPT}$ results for independent set and dominating set are for the simultaneous interval number plus solution size. In contrast, both problems are known to be $\mathsf{W}[1]$-hard for linear mim-width plus solution size.
format Preprint
id arxiv_https___arxiv_org_abs_2404_10670
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle The Simultaneous Interval Number: A New Width Parameter that Measures the Similarity to Interval Graphs
Beisegel, Jesse
Chiarelli, Nina
Köhler, Ekkehard
Milanič, Martin
Muršič, Peter
Scheffler, Robert
Discrete Mathematics
Computational Complexity
Data Structures and Algorithms
Combinatorics
We propose a novel way of generalizing the class of interval graphs, via a graph width parameter called the simultaneous interval number. This parameter is related to the simultaneous representation problem for interval graphs and defined as the smallest number $d$ of labels such that the graph admits a $d$-simultaneous interval representation, that is, an assignment of intervals and label sets to the vertices such that two vertices are adjacent if and only if the corresponding intervals, as well as their label sets, intersect. We show that this parameter is $\mathsf{NP}$-hard to compute and give several bounds for the parameter, showing in particular that it is sandwiched between pathwidth and linear mim-width. For classes of graphs with bounded parameter values, assuming that the graph is equipped with a simultaneous interval representation with a constant number of labels, we give $\mathsf{FPT}$ algorithms for the clique, independent set, and dominating set problems, and hardness results for the independent dominating set and coloring problems. The $\mathsf{FPT}$ results for independent set and dominating set are for the simultaneous interval number plus solution size. In contrast, both problems are known to be $\mathsf{W}[1]$-hard for linear mim-width plus solution size.
title The Simultaneous Interval Number: A New Width Parameter that Measures the Similarity to Interval Graphs
topic Discrete Mathematics
Computational Complexity
Data Structures and Algorithms
Combinatorics
url https://arxiv.org/abs/2404.10670