The Complexity of Helly-$B_{1}$ EPG Graph Recognition

Golumbic, Lipshteyn, and Stern defined in 2009 the class of EPG graphs, the intersection graph class of edge paths on a grid. An EPG graph $G$ is a graph that admits a representation where its vertices correspond to paths in a grid $Q$, such that two vertices of $G$ are adjacent if and only if their...

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Main Authors: Claudson F. Bornstein, Martin Charles Golumbic, Tanilson D. Santos, Uéverton S. Souza, Jayme L. Szwarcfiter
Format: Article
Language:English
Published: Discrete Mathematics & Theoretical Computer Science 2020-06-01
Series:Discrete Mathematics & Theoretical Computer Science
Subjects:
Online Access:https://dmtcs.episciences.org/5603/pdf
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author Claudson F. Bornstein
Martin Charles Golumbic
Tanilson D. Santos
Uéverton S. Souza
Jayme L. Szwarcfiter
author_facet Claudson F. Bornstein
Martin Charles Golumbic
Tanilson D. Santos
Uéverton S. Souza
Jayme L. Szwarcfiter
author_sort Claudson F. Bornstein
collection DOAJ
description Golumbic, Lipshteyn, and Stern defined in 2009 the class of EPG graphs, the intersection graph class of edge paths on a grid. An EPG graph $G$ is a graph that admits a representation where its vertices correspond to paths in a grid $Q$, such that two vertices of $G$ are adjacent if and only if their corresponding paths in $Q$ have a common edge. If the paths in the representation have at most $k$ bends, we say that it is a $B_k$-EPG representation. A collection $C$ of sets satisfies the Helly property when every sub-collection of $C$ that is pairwise intersecting has at least one common element. In this paper, we show that given a graph $G$ and an integer $k$, the problem of determining whether $G$ admits a $B_k$-EPG representation whose edge-intersections of paths satisfy the Helly property, so-called Helly-$B_k$-EPG representation, is in NP, for every $k$ bounded by a polynomial function of $|V(G)|$. Moreover, we show that the problem of recognizing Helly-$B_1$-EPG graphs is NP-complete, and it remains NP-complete even when restricted to 2-apex and 3-degenerate graphs.
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spelling doaj.art-da06a09c50fb450c9c4cd64e40660d252024-03-07T15:40:51ZengDiscrete Mathematics & Theoretical Computer ScienceDiscrete Mathematics & Theoretical Computer Science1365-80502020-06-01vol. 22 no. 1Graph Theory10.23638/DMTCS-22-1-195603The Complexity of Helly-$B_{1}$ EPG Graph RecognitionClaudson F. BornsteinMartin Charles GolumbicTanilson D. SantosUéverton S. SouzaJayme L. SzwarcfiterGolumbic, Lipshteyn, and Stern defined in 2009 the class of EPG graphs, the intersection graph class of edge paths on a grid. An EPG graph $G$ is a graph that admits a representation where its vertices correspond to paths in a grid $Q$, such that two vertices of $G$ are adjacent if and only if their corresponding paths in $Q$ have a common edge. If the paths in the representation have at most $k$ bends, we say that it is a $B_k$-EPG representation. A collection $C$ of sets satisfies the Helly property when every sub-collection of $C$ that is pairwise intersecting has at least one common element. In this paper, we show that given a graph $G$ and an integer $k$, the problem of determining whether $G$ admits a $B_k$-EPG representation whose edge-intersections of paths satisfy the Helly property, so-called Helly-$B_k$-EPG representation, is in NP, for every $k$ bounded by a polynomial function of $|V(G)|$. Moreover, we show that the problem of recognizing Helly-$B_1$-EPG graphs is NP-complete, and it remains NP-complete even when restricted to 2-apex and 3-degenerate graphs.https://dmtcs.episciences.org/5603/pdfcomputer science - discrete mathematicscomputer science - computational complexitycomputer science - data structures and algorithms
spellingShingle Claudson F. Bornstein
Martin Charles Golumbic
Tanilson D. Santos
Uéverton S. Souza
Jayme L. Szwarcfiter
The Complexity of Helly-$B_{1}$ EPG Graph Recognition
Discrete Mathematics & Theoretical Computer Science
computer science - discrete mathematics
computer science - computational complexity
computer science - data structures and algorithms
title The Complexity of Helly-$B_{1}$ EPG Graph Recognition
title_full The Complexity of Helly-$B_{1}$ EPG Graph Recognition
title_fullStr The Complexity of Helly-$B_{1}$ EPG Graph Recognition
title_full_unstemmed The Complexity of Helly-$B_{1}$ EPG Graph Recognition
title_short The Complexity of Helly-$B_{1}$ EPG Graph Recognition
title_sort complexity of helly b 1 epg graph recognition
topic computer science - discrete mathematics
computer science - computational complexity
computer science - data structures and algorithms
url https://dmtcs.episciences.org/5603/pdf
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