Exotic spherical flexible octahedra and counterexamples to the Modified Bellows Conjecture

Fuente: arXiv
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Autor principal: Gaifullin, Alexander A.
Formato: Preprint
Publicado: 2025
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author Gaifullin, Alexander A.
author_facet Gaifullin, Alexander A.
contents In 2014 the author showed that in the three-dimensional spherical space, alongside with three classical types of flexible octahedra constructed by Bricard, there exists a new type of flexible octahedra, which was called exotic. In the present paper we give a geometric construction for exotic flexible octahedra, describe their configuration spaces, and calculate their volumes. We show that the volume of an exotic flexible octahedron is nonconstant during the flexion, and moreover the volume remains nonconstant if we replace any set of vertices of the octahedron with their antipodes. So exotic flexible octahedra are counterexamples to the Modified Bellows Conjecture proposed by the author in 2015.
format Preprint
id arxiv_https___arxiv_org_abs_2503_09582
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Exotic spherical flexible octahedra and counterexamples to the Modified Bellows Conjecture
Gaifullin, Alexander A.
Metric Geometry
52C25 (Primary), 51M25, 52B10 (Secondary)
In 2014 the author showed that in the three-dimensional spherical space, alongside with three classical types of flexible octahedra constructed by Bricard, there exists a new type of flexible octahedra, which was called exotic. In the present paper we give a geometric construction for exotic flexible octahedra, describe their configuration spaces, and calculate their volumes. We show that the volume of an exotic flexible octahedron is nonconstant during the flexion, and moreover the volume remains nonconstant if we replace any set of vertices of the octahedron with their antipodes. So exotic flexible octahedra are counterexamples to the Modified Bellows Conjecture proposed by the author in 2015.
title Exotic spherical flexible octahedra and counterexamples to the Modified Bellows Conjecture
topic Metric Geometry
52C25 (Primary), 51M25, 52B10 (Secondary)
url https://arxiv.org/abs/2503.09582