Geometric Thickness of Multigraphs is $\exists \mathbb{R}$-complete

Fuente: arXiv
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Hauptverfasser: Förster, Henry, Kindermann, Philipp, Miltzow, Tillmann, Parada, Irene, Terziadis, Soeren, Vogtenhuber, Birgit
Format: Preprint
Veröffentlicht: 2023
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author Förster, Henry
Kindermann, Philipp
Miltzow, Tillmann
Parada, Irene
Terziadis, Soeren
Vogtenhuber, Birgit
author_facet Förster, Henry
Kindermann, Philipp
Miltzow, Tillmann
Parada, Irene
Terziadis, Soeren
Vogtenhuber, Birgit
contents We say that a (multi)graph $G = (V,E)$ has geometric thickness $t$ if there exists a straight-line drawing $φ: V \rightarrow \mathbb{R}^2$ and a $t$-coloring of its edges where no two edges sharing a point in their relative interior have the same color. The \textsc{Geometric Thickness} problem asks whether a given multigraph has geometric thickness at most $t$. This problem was shown to be NP-hard for $t=2$ [Durocher, Gethner, and Mondal, CG 2016]. In this paper, we settle the computational complexity of \textsc{Geometric Thickness} by showing that it is $\exists \mathbb{R}$-complete already for thickness $30$. Moreover, our reduction shows that the problem is $\exists \mathbb{R}$-complete for $4392$-planar graphs, where a graph is $k$-planar if it admits a topological drawing with at most $k$ crossings per edge. In the course of our paper, we answer previous questions on geometric thickness and on other related problems, in particular that simultaneous graph embeddings of $31$ edge-disjoint graphs and pseudo-segment stretchability with chromatic number $30$ are $\exists \mathbb{R}$-complete.
format Preprint
id arxiv_https___arxiv_org_abs_2312_05010
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle Geometric Thickness of Multigraphs is $\exists \mathbb{R}$-complete
Förster, Henry
Kindermann, Philipp
Miltzow, Tillmann
Parada, Irene
Terziadis, Soeren
Vogtenhuber, Birgit
Computational Geometry
Discrete Mathematics
Data Structures and Algorithms
We say that a (multi)graph $G = (V,E)$ has geometric thickness $t$ if there exists a straight-line drawing $φ: V \rightarrow \mathbb{R}^2$ and a $t$-coloring of its edges where no two edges sharing a point in their relative interior have the same color. The \textsc{Geometric Thickness} problem asks whether a given multigraph has geometric thickness at most $t$. This problem was shown to be NP-hard for $t=2$ [Durocher, Gethner, and Mondal, CG 2016]. In this paper, we settle the computational complexity of \textsc{Geometric Thickness} by showing that it is $\exists \mathbb{R}$-complete already for thickness $30$. Moreover, our reduction shows that the problem is $\exists \mathbb{R}$-complete for $4392$-planar graphs, where a graph is $k$-planar if it admits a topological drawing with at most $k$ crossings per edge. In the course of our paper, we answer previous questions on geometric thickness and on other related problems, in particular that simultaneous graph embeddings of $31$ edge-disjoint graphs and pseudo-segment stretchability with chromatic number $30$ are $\exists \mathbb{R}$-complete.
title Geometric Thickness of Multigraphs is $\exists \mathbb{R}$-complete
topic Computational Geometry
Discrete Mathematics
Data Structures and Algorithms
url https://arxiv.org/abs/2312.05010