Homotopy Type of the Space of Fibrations of the Three-sphere by Simple Closed Curves

Fuente: arXiv
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Main Authors: Deturck, Dennis, Fang, Ziqi, Gluck, Herman, Lichtenfelz, Leandro, Merling, Mona, Wang, Yi, Yang, Jingye
Format: Preprint
Published: 2025
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_version_ 1866911088042311680
author Deturck, Dennis
Fang, Ziqi
Gluck, Herman
Lichtenfelz, Leandro
Merling, Mona
Wang, Yi
Yang, Jingye
author_facet Deturck, Dennis
Fang, Ziqi
Gluck, Herman
Lichtenfelz, Leandro
Merling, Mona
Wang, Yi
Yang, Jingye
contents We show that the moduli space of all smooth fibrations of a three-sphere by simple closed curves has the homotopy type of a disjoint union of a pair of two-spheres if the fibers are oriented, and of a pair of real projective planes if unoriented, the same as for its finite-dimensional subspace of Hopf fibrations by parallel great circles. This moduli space is the quotient of the diffeomorphism group of the three-sphere (a Fréchet Lie group) by its subgroup of automorphisms of the Hopf fibration, which we show is a smooth Fréchet submanifold of the diffeomorphism group. Then we show that the moduli space, already known to be a Fréchet manifold by [HKMR12], can be modeled on the concrete Fréchet space of vector fields on the three-sphere which are "horizontal" and "balanced" with respect to a given Hopf fibration, and see how the structure of this moduli space helps us to determine its homotopy type.
format Preprint
id arxiv_https___arxiv_org_abs_2508_01185
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Homotopy Type of the Space of Fibrations of the Three-sphere by Simple Closed Curves
Deturck, Dennis
Fang, Ziqi
Gluck, Herman
Lichtenfelz, Leandro
Merling, Mona
Wang, Yi
Yang, Jingye
Geometric Topology
Algebraic Topology
Differential Geometry
58B05 (Primary) 58B10, 57R30 (Secondary)
We show that the moduli space of all smooth fibrations of a three-sphere by simple closed curves has the homotopy type of a disjoint union of a pair of two-spheres if the fibers are oriented, and of a pair of real projective planes if unoriented, the same as for its finite-dimensional subspace of Hopf fibrations by parallel great circles. This moduli space is the quotient of the diffeomorphism group of the three-sphere (a Fréchet Lie group) by its subgroup of automorphisms of the Hopf fibration, which we show is a smooth Fréchet submanifold of the diffeomorphism group. Then we show that the moduli space, already known to be a Fréchet manifold by [HKMR12], can be modeled on the concrete Fréchet space of vector fields on the three-sphere which are "horizontal" and "balanced" with respect to a given Hopf fibration, and see how the structure of this moduli space helps us to determine its homotopy type.
title Homotopy Type of the Space of Fibrations of the Three-sphere by Simple Closed Curves
topic Geometric Topology
Algebraic Topology
Differential Geometry
58B05 (Primary) 58B10, 57R30 (Secondary)
url https://arxiv.org/abs/2508.01185