Flip Graphs of Pseudo-Triangulations With Face Degree at Most 4

Fuente: arXiv
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Autores principales: Löffler, Maarten, Mchedlidze, Tamara, Orden, David, Tkadlec, Josef, Wulms, Jules
Formato: Preprint
Publicado: 2024
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author Löffler, Maarten
Mchedlidze, Tamara
Orden, David
Tkadlec, Josef
Wulms, Jules
author_facet Löffler, Maarten
Mchedlidze, Tamara
Orden, David
Tkadlec, Josef
Wulms, Jules
contents A pseudo-triangle is a simple polygon with exactly three convex vertices, and all other vertices (if any) are distributed on three concave chains. A pseudo-triangulation~$\mathcal{T}$ of a point set~$P$ in~$\mathbb{R}^2$ is a partitioning of the convex hull of~$P$ into pseudo-triangles, such that the union of the vertices of the pseudo-triangles is exactly~$P$. We call a size-4 pseudo-triangle a dart. For a fixed $k\geq 1$, we study $k$-dart pseudo-triangulations ($k$-DPTs), that is, pseudo-triangulations in which exactly $k$ faces are darts and all other faces are triangles. We study the flip graph for such pseudo-triangulations, in which a flip exchanges the diagonals of a pseudo-quadrilatral. Our results are as follows. We prove that the flip graph of $1$-DPTs is generally not connected, and show how to compute its connected components. Furthermore, for $k$-DPTs on a point configuration called the double chain we analyze the structure of the flip graph on a more fine-grained level.
format Preprint
id arxiv_https___arxiv_org_abs_2402_12357
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Flip Graphs of Pseudo-Triangulations With Face Degree at Most 4
Löffler, Maarten
Mchedlidze, Tamara
Orden, David
Tkadlec, Josef
Wulms, Jules
Computational Geometry
A pseudo-triangle is a simple polygon with exactly three convex vertices, and all other vertices (if any) are distributed on three concave chains. A pseudo-triangulation~$\mathcal{T}$ of a point set~$P$ in~$\mathbb{R}^2$ is a partitioning of the convex hull of~$P$ into pseudo-triangles, such that the union of the vertices of the pseudo-triangles is exactly~$P$. We call a size-4 pseudo-triangle a dart. For a fixed $k\geq 1$, we study $k$-dart pseudo-triangulations ($k$-DPTs), that is, pseudo-triangulations in which exactly $k$ faces are darts and all other faces are triangles. We study the flip graph for such pseudo-triangulations, in which a flip exchanges the diagonals of a pseudo-quadrilatral. Our results are as follows. We prove that the flip graph of $1$-DPTs is generally not connected, and show how to compute its connected components. Furthermore, for $k$-DPTs on a point configuration called the double chain we analyze the structure of the flip graph on a more fine-grained level.
title Flip Graphs of Pseudo-Triangulations With Face Degree at Most 4
topic Computational Geometry
url https://arxiv.org/abs/2402.12357