TY - JOUR

T1 - Differentiable sphere theorems whose comparison spaces are standard spheres or exotic ones∗†

AU - Kondo, Kei

AU - Tanaka, Minoru

N1 - Publisher Copyright:
Copyright © 2017, The Authors. All rights reserved.
Copyright:
Copyright 2020 Elsevier B.V., All rights reserved.

PY - 2017/5/29

Y1 - 2017/5/29

N2 - We show that for an arbitrarily given closed Riemannian manifold M admitting a point p ∈ M with a single cut point, every closed Riemannian manifold N admitting a point q ∈ N with a single cut point is diffeomorphic to M if the radial curvatures of N at q are sufficiently close in the sense of L1-norm to those of M at p. Our result hence not only produces a weak version of the Cartan–Ambrose–Hicks theorem in the case where underlying manifolds admit a point with a single cut point, but also is a kind of a weak version of the Blaschke conjecture for spheres proved by Berger. In particular that result generalizes one of theorems in Cheeger’s Ph.D. Thesis in that case. Remark that every exotic sphere of dimension > 4 admits a metric such that there is a point whose cut locus consists of a single point.53C20, 57R55 (Primary), 49J52, 57R12 (Secondary)

AB - We show that for an arbitrarily given closed Riemannian manifold M admitting a point p ∈ M with a single cut point, every closed Riemannian manifold N admitting a point q ∈ N with a single cut point is diffeomorphic to M if the radial curvatures of N at q are sufficiently close in the sense of L1-norm to those of M at p. Our result hence not only produces a weak version of the Cartan–Ambrose–Hicks theorem in the case where underlying manifolds admit a point with a single cut point, but also is a kind of a weak version of the Blaschke conjecture for spheres proved by Berger. In particular that result generalizes one of theorems in Cheeger’s Ph.D. Thesis in that case. Remark that every exotic sphere of dimension > 4 admits a metric such that there is a point whose cut locus consists of a single point.53C20, 57R55 (Primary), 49J52, 57R12 (Secondary)

KW - Bi-Lipschitz homeomorphism

KW - Differentiable sphere theorem

KW - Exotic spheres

KW - Radial curvature

KW - The Blaschke conjecture for spheres

KW - The Cartan–Ambrose–Hicks theorem

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M3 - Article

AN - SCOPUS:85093035789

JO - [No source information available]

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SN - 0402-1215

ER -