Flippable Edges in Triangulations on Surfaces

Concerning diagonal flips on triangulations, Gao et al. showed that any triangulation G on the sphere with n ≥ 5 vertices has at least n − 2 flippable edges. Furthermore, if G has minimum degree at least 4 and n ≥ 9, then G has at least 2n + 3 flippable edges. In this paper, we give a simpler proof...

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Main Authors: Ikegami Daiki, Nakamoto Atsuhiro
Format: Article
Language:English
Published: University of Zielona Góra 2022-11-01
Series:Discussiones Mathematicae Graph Theory
Subjects:
Online Access:https://doi.org/10.7151/dmgt.2377
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author Ikegami Daiki
Nakamoto Atsuhiro
author_facet Ikegami Daiki
Nakamoto Atsuhiro
author_sort Ikegami Daiki
collection DOAJ
description Concerning diagonal flips on triangulations, Gao et al. showed that any triangulation G on the sphere with n ≥ 5 vertices has at least n − 2 flippable edges. Furthermore, if G has minimum degree at least 4 and n ≥ 9, then G has at least 2n + 3 flippable edges. In this paper, we give a simpler proof of their results, and extend them to the case of the projective plane, the torus and the Klein bottle. Finally, we give an estimation for the number of flippable edges of a triangulation on general surfaces, using the notion of irreducible triangulations.
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spelling doaj.art-812ca840e3ec4987832f18f749841add2023-09-02T09:07:26ZengUniversity of Zielona GóraDiscussiones Mathematicae Graph Theory2083-58922022-11-014241041105910.7151/dmgt.2377Flippable Edges in Triangulations on SurfacesIkegami Daiki0Nakamoto Atsuhiro1Graduate School of Environment and Information Science, Yokohama National University, 79-7 Tokiwadai, Hodogaya-ku, Yokohama240-8501, JapanFaculty of Environment and Information Science, Yokohama National University, 79-7 Tokiwadai, Hodogaya-ku, Yokohama240-8501, JapanConcerning diagonal flips on triangulations, Gao et al. showed that any triangulation G on the sphere with n ≥ 5 vertices has at least n − 2 flippable edges. Furthermore, if G has minimum degree at least 4 and n ≥ 9, then G has at least 2n + 3 flippable edges. In this paper, we give a simpler proof of their results, and extend them to the case of the projective plane, the torus and the Klein bottle. Finally, we give an estimation for the number of flippable edges of a triangulation on general surfaces, using the notion of irreducible triangulations.https://doi.org/10.7151/dmgt.2377triangulationdiagonal flipsurface05c10
spellingShingle Ikegami Daiki
Nakamoto Atsuhiro
Flippable Edges in Triangulations on Surfaces
Discussiones Mathematicae Graph Theory
triangulation
diagonal flip
surface
05c10
title Flippable Edges in Triangulations on Surfaces
title_full Flippable Edges in Triangulations on Surfaces
title_fullStr Flippable Edges in Triangulations on Surfaces
title_full_unstemmed Flippable Edges in Triangulations on Surfaces
title_short Flippable Edges in Triangulations on Surfaces
title_sort flippable edges in triangulations on surfaces
topic triangulation
diagonal flip
surface
05c10
url https://doi.org/10.7151/dmgt.2377
work_keys_str_mv AT ikegamidaiki flippableedgesintriangulationsonsurfaces
AT nakamotoatsuhiro flippableedgesintriangulationsonsurfaces