$\mathbb{S}^6$ (or any of $\mathbb{S}^2 \times \mathbb{S}^4$, $\mathbb{S}^2\times\mathbb{S}^6$, or $\mathbb{S}^6\times \mathbb{S}^6$, respectively) is not diffeomorphic to a complex manifold

Fuente: arXiv
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Auteur principal: Simanca, Santiago R
Format: Preprint
Publié: 2022
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author Simanca, Santiago R
author_facet Simanca, Santiago R
contents We identify all metrics on a closed $n$-manifold with their Nash isometric embeddings into a standard sphere of large, but fixed dimension, and use the Palais' isotopic extension theorem to identify their deformations with the isotopic deformations of their embeddings, the deformations of metrics in a conformal class identified with their corresponding isotopic conformal deformations. If $n\geq 3$, we characterize metrics of constant scalar curvature in terms of properties of extrinsic quantities of their associated embeddings, and prove that any metric on the manifold of constant positive scalar curvature, which can be minimally embedded into this background sphere, is a Yamabe metric in its conformal class. We then use Simons' gap theorem to study the extrinsic quantities of almost complex Hermitian deformations, by Yamabe metrics, of the standard minimal almost complex isometric embeddings of $\mb{S}^6$, $\mb{S}^2 \times \mb{S}^4$, $\mb{S}^2\times\mb{S}^6$, and $\mb{S}^6\times \mb{S}^6$, respectively, and prove that none of these manifolds carry integrable almost complex structures. :
format Preprint
id arxiv_https___arxiv_org_abs_2204_12628
institution arXiv
publishDate 2022
record_format arxiv
spellingShingle $\mathbb{S}^6$ (or any of $\mathbb{S}^2 \times \mathbb{S}^4$, $\mathbb{S}^2\times\mathbb{S}^6$, or $\mathbb{S}^6\times \mathbb{S}^6$, respectively) is not diffeomorphic to a complex manifold
Simanca, Santiago R
Differential Geometry
53C15, 53C20, 58E11
We identify all metrics on a closed $n$-manifold with their Nash isometric embeddings into a standard sphere of large, but fixed dimension, and use the Palais' isotopic extension theorem to identify their deformations with the isotopic deformations of their embeddings, the deformations of metrics in a conformal class identified with their corresponding isotopic conformal deformations. If $n\geq 3$, we characterize metrics of constant scalar curvature in terms of properties of extrinsic quantities of their associated embeddings, and prove that any metric on the manifold of constant positive scalar curvature, which can be minimally embedded into this background sphere, is a Yamabe metric in its conformal class. We then use Simons' gap theorem to study the extrinsic quantities of almost complex Hermitian deformations, by Yamabe metrics, of the standard minimal almost complex isometric embeddings of $\mb{S}^6$, $\mb{S}^2 \times \mb{S}^4$, $\mb{S}^2\times\mb{S}^6$, and $\mb{S}^6\times \mb{S}^6$, respectively, and prove that none of these manifolds carry integrable almost complex structures. :
title $\mathbb{S}^6$ (or any of $\mathbb{S}^2 \times \mathbb{S}^4$, $\mathbb{S}^2\times\mathbb{S}^6$, or $\mathbb{S}^6\times \mathbb{S}^6$, respectively) is not diffeomorphic to a complex manifold
topic Differential Geometry
53C15, 53C20, 58E11
url https://arxiv.org/abs/2204.12628