Optimal Orthogonal Drawings in Linear Time

Fuente: arXiv
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Main Authors: Didimo, Walter, Liotta, Giuseppe, Ortali, Giacomo, Patrignani, Maurizio
Format: Preprint
Published: 2025
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author Didimo, Walter
Liotta, Giuseppe
Ortali, Giacomo
Patrignani, Maurizio
author_facet Didimo, Walter
Liotta, Giuseppe
Ortali, Giacomo
Patrignani, Maurizio
contents A planar orthogonal drawing Γ of a connected planar graph G is a geometric representation of G such that the vertices are drawn as distinct points of the plane, the edges are drawn as chains of horizontal and vertical segments, and no two edges intersect except at common end-points. A bend of Γ is a point of an edge where a horizontal and a vertical segment meet. Drawing Γ is bend-minimum if it has the minimum number of bends over all possible planar orthogonal drawings of G. Its curve complexity is the maximum number of bends per edge. In this paper we present a linear-time algorithm for the computation of planar orthogonal drawings of 3-graphs (i.e., graphs with vertex-degree at most three), that minimizes both the total number of bends and the curve complexity. The algorithm works in the so-called variable embedding setting, that is, it can choose among the exponentially many planar embeddings of the input graph. While the time complexity of minimizing the total number of bends of a planar orthogonal drawing of a 3-graph in the variable embedding settings is a long standing, widely studied, open question, the existence of an orthogonal drawing that is optimal both in the total number of bends and in the curve complexity was previously unknown. Our result combines several graph decomposition techniques, novel data-structures, and efficient approaches to re-rooting decomposition trees.
format Preprint
id arxiv_https___arxiv_org_abs_2502_03309
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Optimal Orthogonal Drawings in Linear Time
Didimo, Walter
Liotta, Giuseppe
Ortali, Giacomo
Patrignani, Maurizio
Computational Geometry
Data Structures and Algorithms
A planar orthogonal drawing Γ of a connected planar graph G is a geometric representation of G such that the vertices are drawn as distinct points of the plane, the edges are drawn as chains of horizontal and vertical segments, and no two edges intersect except at common end-points. A bend of Γ is a point of an edge where a horizontal and a vertical segment meet. Drawing Γ is bend-minimum if it has the minimum number of bends over all possible planar orthogonal drawings of G. Its curve complexity is the maximum number of bends per edge. In this paper we present a linear-time algorithm for the computation of planar orthogonal drawings of 3-graphs (i.e., graphs with vertex-degree at most three), that minimizes both the total number of bends and the curve complexity. The algorithm works in the so-called variable embedding setting, that is, it can choose among the exponentially many planar embeddings of the input graph. While the time complexity of minimizing the total number of bends of a planar orthogonal drawing of a 3-graph in the variable embedding settings is a long standing, widely studied, open question, the existence of an orthogonal drawing that is optimal both in the total number of bends and in the curve complexity was previously unknown. Our result combines several graph decomposition techniques, novel data-structures, and efficient approaches to re-rooting decomposition trees.
title Optimal Orthogonal Drawings in Linear Time
topic Computational Geometry
Data Structures and Algorithms
url https://arxiv.org/abs/2502.03309