Napoleonic Constructions in the Hyperbolic Plane

Fuente: arXiv
Salvato in:
Dettagli Bibliografici
Autori principali: Dipierro, Serena, Noakes, Lyle, Valdinoci, Enrico
Natura: Preprint
Pubblicazione: 2025
Soggetti:
Accesso online:
Tags: Aggiungi Tag
Nessun Tag, puoi essere il primo ad aggiungerne!!
_version_ 1866913704984969216
author Dipierro, Serena
Noakes, Lyle
Valdinoci, Enrico
author_facet Dipierro, Serena
Noakes, Lyle
Valdinoci, Enrico
contents In the Euclidean setting, Napoleon's Theorem states that if one constructs an equilateral triangle on either the outside or the inside of each side of a given triangle and then connects the barycenters of those three new triangles, the resulting triangle happens to be equilateral. The case of spherical triangles has been recently shown to be different: on the sphere, besides equilateral triangles, a necessary and sufficient condition for a given triangle to enjoy the above Napoleonic property is that its congruence class should lie on a suitable surface (namely, an ellipsoid in suitable coordinates). In this article we show that the hyperbolic case is significantly different from both the Euclidean and the spherical setting. Specifically, we establish here that the hyperbolic plane does not admit any Napoleonic triangle, except the equilateral ones. Furthermore, we prove that iterated Napoleonization of any triangle causes it to become smaller and smaller, more and more equilateral and converge to a single point in the limit.
format Preprint
id arxiv_https___arxiv_org_abs_2502_16964
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Napoleonic Constructions in the Hyperbolic Plane
Dipierro, Serena
Noakes, Lyle
Valdinoci, Enrico
Analysis of PDEs
Differential Geometry
Metric Geometry
In the Euclidean setting, Napoleon's Theorem states that if one constructs an equilateral triangle on either the outside or the inside of each side of a given triangle and then connects the barycenters of those three new triangles, the resulting triangle happens to be equilateral. The case of spherical triangles has been recently shown to be different: on the sphere, besides equilateral triangles, a necessary and sufficient condition for a given triangle to enjoy the above Napoleonic property is that its congruence class should lie on a suitable surface (namely, an ellipsoid in suitable coordinates). In this article we show that the hyperbolic case is significantly different from both the Euclidean and the spherical setting. Specifically, we establish here that the hyperbolic plane does not admit any Napoleonic triangle, except the equilateral ones. Furthermore, we prove that iterated Napoleonization of any triangle causes it to become smaller and smaller, more and more equilateral and converge to a single point in the limit.
title Napoleonic Constructions in the Hyperbolic Plane
topic Analysis of PDEs
Differential Geometry
Metric Geometry
url https://arxiv.org/abs/2502.16964