The Exact Spanning Ratio of the Parallelogram Delaunay Graph

Fuente: arXiv
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Main Authors: Bose, Prosenjit, De Carufel, Jean-Lou, Njoo, Sandrine
Format: Preprint
Published: 2023
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author Bose, Prosenjit
De Carufel, Jean-Lou
Njoo, Sandrine
author_facet Bose, Prosenjit
De Carufel, Jean-Lou
Njoo, Sandrine
contents Finding the exact spanning ratio of a Delaunay graph has been one of the longstanding open problems in Computational Geometry. Currently there are only four convex shapes for which the exact spanning ratio of their Delaunay graph is known: the equilateral triangle, the square, the regular hexagon and the rectangle. In this paper, we show the exact spanning ratio of the parallelogram Delaunay graph, making the parallelogram the fifth convex shape for which an exact bound is known. The worst-case spanning ratio is exactly $$\frac{\sqrt{2}\sqrt{1+A^2+2A\cos(θ_0)+(A+\cos(θ_0))\sqrt{1+A^2+2A\cos(θ_0)}}}{\sin(θ_0)} .$$ where $A$ is the aspect ratio and $θ_0$ is the non-obtuse angle of the parallelogram. Moreover, we show how to construct a parallelogram Delaunay graph whose spanning ratio matches the above mentioned spanning ratio.
format Preprint
id arxiv_https___arxiv_org_abs_2312_14305
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle The Exact Spanning Ratio of the Parallelogram Delaunay Graph
Bose, Prosenjit
De Carufel, Jean-Lou
Njoo, Sandrine
Computational Geometry
Finding the exact spanning ratio of a Delaunay graph has been one of the longstanding open problems in Computational Geometry. Currently there are only four convex shapes for which the exact spanning ratio of their Delaunay graph is known: the equilateral triangle, the square, the regular hexagon and the rectangle. In this paper, we show the exact spanning ratio of the parallelogram Delaunay graph, making the parallelogram the fifth convex shape for which an exact bound is known. The worst-case spanning ratio is exactly $$\frac{\sqrt{2}\sqrt{1+A^2+2A\cos(θ_0)+(A+\cos(θ_0))\sqrt{1+A^2+2A\cos(θ_0)}}}{\sin(θ_0)} .$$ where $A$ is the aspect ratio and $θ_0$ is the non-obtuse angle of the parallelogram. Moreover, we show how to construct a parallelogram Delaunay graph whose spanning ratio matches the above mentioned spanning ratio.
title The Exact Spanning Ratio of the Parallelogram Delaunay Graph
topic Computational Geometry
url https://arxiv.org/abs/2312.14305