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

Kei Kondo, Minoru Tanaka

Research output: Contribution to journalArticlepeer-review

Abstract

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)

Original languageEnglish
JournalUnknown Journal
Publication statusPublished - May 29 2017
Externally publishedYes

Keywords

  • Bi-Lipschitz homeomorphism
  • Differentiable sphere theorem
  • Exotic spheres
  • Radial curvature
  • The Blaschke conjecture for spheres
  • The Cartan–Ambrose–Hicks theorem

ASJC Scopus subject areas

  • General

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