Topology of closed asymptotic curves on negatively curved surfaces

Fuente: arXiv
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Main Authors: Ghomi, Mohammad, Raffaelli, Matteo
Format: Preprint
Published: 2024
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author Ghomi, Mohammad
Raffaelli, Matteo
author_facet Ghomi, Mohammad
Raffaelli, Matteo
contents Motivated by Nirenberg's problem on isometric rigidity of tight surfaces, we study closed asymptotic curves $Γ$ on negatively curved surfaces $M$ in Euclidean $3$-space. In particular, using Călugăreanu's theorem, we obtain a formula for the linking number $Lk(Γ,n)$ of $Γ$ with the normal $n$ of $M$. It follows that when $Lk(Γ, n)=0$, $Γ$ cannot have any locally star-shaped planar projections with vanishing crossing number, which extends observations of Kovaleva, Panov and Arnold. These results hold also for curves with nonvanishing torsion and their binormal vector field. Furthermore we construct an example where $n$ is injective but $Lk(Γ, n)\neq 0$, and discuss various restrictions on $Γ$ when $n$ is injective.
format Preprint
id arxiv_https___arxiv_org_abs_2412_19266
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Topology of closed asymptotic curves on negatively curved surfaces
Ghomi, Mohammad
Raffaelli, Matteo
Differential Geometry
Analysis of PDEs
Geometric Topology
Primary 53A04, 53A05, Secondary 57K10, 35L10
Motivated by Nirenberg's problem on isometric rigidity of tight surfaces, we study closed asymptotic curves $Γ$ on negatively curved surfaces $M$ in Euclidean $3$-space. In particular, using Călugăreanu's theorem, we obtain a formula for the linking number $Lk(Γ,n)$ of $Γ$ with the normal $n$ of $M$. It follows that when $Lk(Γ, n)=0$, $Γ$ cannot have any locally star-shaped planar projections with vanishing crossing number, which extends observations of Kovaleva, Panov and Arnold. These results hold also for curves with nonvanishing torsion and their binormal vector field. Furthermore we construct an example where $n$ is injective but $Lk(Γ, n)\neq 0$, and discuss various restrictions on $Γ$ when $n$ is injective.
title Topology of closed asymptotic curves on negatively curved surfaces
topic Differential Geometry
Analysis of PDEs
Geometric Topology
Primary 53A04, 53A05, Secondary 57K10, 35L10
url https://arxiv.org/abs/2412.19266