The total absolute curvature of closed curves with singularities

Fuente: arXiv
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Main Authors: Honda, Atsufumi, Tanaka, Chisa, Yamauchi, Yuta
Format: Preprint
Published: 2024
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author Honda, Atsufumi
Tanaka, Chisa
Yamauchi, Yuta
author_facet Honda, Atsufumi
Tanaka, Chisa
Yamauchi, Yuta
contents In this paper, we give a generalization of Fenchel's theorem for closed curves as frontals in Euclidean space $\mathbb{R}^n$. We prove that, for a non-co-orientable closed frontal in $\mathbb{R}^n$, its total absolute curvature is greater than or equal to $π$. It is equal to $π$ if and only if the curve is a planar locally $L$-convex closed frontal whose rotation index is $1/2$ or $-1/2$. Furthermore, if the equality holds and if every singular point is a cusp, then the number $N$ of cusps is an odd integer greater than or equal to $3$, and $N=3$ holds if and only if the curve is simple.
format Preprint
id arxiv_https___arxiv_org_abs_2403_00487
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle The total absolute curvature of closed curves with singularities
Honda, Atsufumi
Tanaka, Chisa
Yamauchi, Yuta
Differential Geometry
Primary 53A04, Secondary 57R45, 53C65, 53C42
In this paper, we give a generalization of Fenchel's theorem for closed curves as frontals in Euclidean space $\mathbb{R}^n$. We prove that, for a non-co-orientable closed frontal in $\mathbb{R}^n$, its total absolute curvature is greater than or equal to $π$. It is equal to $π$ if and only if the curve is a planar locally $L$-convex closed frontal whose rotation index is $1/2$ or $-1/2$. Furthermore, if the equality holds and if every singular point is a cusp, then the number $N$ of cusps is an odd integer greater than or equal to $3$, and $N=3$ holds if and only if the curve is simple.
title The total absolute curvature of closed curves with singularities
topic Differential Geometry
Primary 53A04, Secondary 57R45, 53C65, 53C42
url https://arxiv.org/abs/2403.00487