On the bend number of circular-arc graphs as edge intersection graphs of paths on a grid
Golumbic, Lipshteyn and Stern [12] proved that every graph can be represented as the edge intersection graph of paths on a grid (EPG graph), i.e., one can associate with each vertex of the graph a nontrivial path on a rectangular grid such that two vertices are adjacent if and only if the correspond...
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todo:paper_0166218X_v234_n_p12_Alcon2023-10-03T15:03:44Z On the bend number of circular-arc graphs as edge intersection graphs of paths on a grid Alcón, L. Bonomo, F. Durán, G. Gutierrez, M. Mazzoleni, M.P. Ries, B. Valencia-Pabon, M. (normal, Helly) circular-arc graphs Edge intersection graphs Forbidden induced subgraphs Paths on a grid Powers of cycles Geometry Graphic methods Circular-arc graph Forbidden induced subgraphs Intersection graph Paths on a grid Powers of cycles Graph theory Golumbic, Lipshteyn and Stern [12] proved that every graph can be represented as the edge intersection graph of paths on a grid (EPG graph), i.e., one can associate with each vertex of the graph a nontrivial path on a rectangular grid such that two vertices are adjacent if and only if the corresponding paths share at least one edge of the grid. For a nonnegative integer k, Bk-EPG graphs are defined as EPG graphs admitting a model in which each path has at most k bends. Circular-arc graphs are intersection graphs of open arcs of a circle. It is easy to see that every circular-arc graph is a B4-EPG graph, by embedding the circle into a rectangle of the grid. In this paper, we prove that circular-arc graphs are B3-EPG, and that there exist circular-arc graphs which are not B2-EPG. If we restrict ourselves to rectangular representations (i.e., the union of the paths used in the model is contained in the boundary of a rectangle of the grid), we obtain EPR (edge intersection of paths in a rectangle) representations. We may define Bk-EPR graphs, k≥0, the same way as Bk-EPG graphs. Circular-arc graphs are clearly B4-EPR graphs and we will show that there exist circular-arc graphs that are not B3-EPR graphs. We also show that normal circular-arc graphs are B2-EPR graphs and that there exist normal circular-arc graphs that are not B1-EPR graphs. Finally, we characterize B1-EPR graphs by a family of minimal forbidden induced subgraphs, and show that they form a subclass of normal Helly circular-arc graphs. © 2016 Elsevier B.V. Fil:Bonomo, F. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. Fil:Durán, G. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. JOUR info:eu-repo/semantics/openAccess http://creativecommons.org/licenses/by/2.5/ar http://hdl.handle.net/20.500.12110/paper_0166218X_v234_n_p12_Alcon |
institution |
Universidad de Buenos Aires |
institution_str |
I-28 |
repository_str |
R-134 |
collection |
Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) |
topic |
(normal, Helly) circular-arc graphs Edge intersection graphs Forbidden induced subgraphs Paths on a grid Powers of cycles Geometry Graphic methods Circular-arc graph Forbidden induced subgraphs Intersection graph Paths on a grid Powers of cycles Graph theory |
spellingShingle |
(normal, Helly) circular-arc graphs Edge intersection graphs Forbidden induced subgraphs Paths on a grid Powers of cycles Geometry Graphic methods Circular-arc graph Forbidden induced subgraphs Intersection graph Paths on a grid Powers of cycles Graph theory Alcón, L. Bonomo, F. Durán, G. Gutierrez, M. Mazzoleni, M.P. Ries, B. Valencia-Pabon, M. On the bend number of circular-arc graphs as edge intersection graphs of paths on a grid |
topic_facet |
(normal, Helly) circular-arc graphs Edge intersection graphs Forbidden induced subgraphs Paths on a grid Powers of cycles Geometry Graphic methods Circular-arc graph Forbidden induced subgraphs Intersection graph Paths on a grid Powers of cycles Graph theory |
description |
Golumbic, Lipshteyn and Stern [12] proved that every graph can be represented as the edge intersection graph of paths on a grid (EPG graph), i.e., one can associate with each vertex of the graph a nontrivial path on a rectangular grid such that two vertices are adjacent if and only if the corresponding paths share at least one edge of the grid. For a nonnegative integer k, Bk-EPG graphs are defined as EPG graphs admitting a model in which each path has at most k bends. Circular-arc graphs are intersection graphs of open arcs of a circle. It is easy to see that every circular-arc graph is a B4-EPG graph, by embedding the circle into a rectangle of the grid. In this paper, we prove that circular-arc graphs are B3-EPG, and that there exist circular-arc graphs which are not B2-EPG. If we restrict ourselves to rectangular representations (i.e., the union of the paths used in the model is contained in the boundary of a rectangle of the grid), we obtain EPR (edge intersection of paths in a rectangle) representations. We may define Bk-EPR graphs, k≥0, the same way as Bk-EPG graphs. Circular-arc graphs are clearly B4-EPR graphs and we will show that there exist circular-arc graphs that are not B3-EPR graphs. We also show that normal circular-arc graphs are B2-EPR graphs and that there exist normal circular-arc graphs that are not B1-EPR graphs. Finally, we characterize B1-EPR graphs by a family of minimal forbidden induced subgraphs, and show that they form a subclass of normal Helly circular-arc graphs. © 2016 Elsevier B.V. |
format |
JOUR |
author |
Alcón, L. Bonomo, F. Durán, G. Gutierrez, M. Mazzoleni, M.P. Ries, B. Valencia-Pabon, M. |
author_facet |
Alcón, L. Bonomo, F. Durán, G. Gutierrez, M. Mazzoleni, M.P. Ries, B. Valencia-Pabon, M. |
author_sort |
Alcón, L. |
title |
On the bend number of circular-arc graphs as edge intersection graphs of paths on a grid |
title_short |
On the bend number of circular-arc graphs as edge intersection graphs of paths on a grid |
title_full |
On the bend number of circular-arc graphs as edge intersection graphs of paths on a grid |
title_fullStr |
On the bend number of circular-arc graphs as edge intersection graphs of paths on a grid |
title_full_unstemmed |
On the bend number of circular-arc graphs as edge intersection graphs of paths on a grid |
title_sort |
on the bend number of circular-arc graphs as edge intersection graphs of paths on a grid |
url |
http://hdl.handle.net/20.500.12110/paper_0166218X_v234_n_p12_Alcon |
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