English

Collapsing to Alexandrov spaces with isolated mild singularities

Differential Geometry 2023-01-18 v2 Metric Geometry

Abstract

Let MjM_j be a sequence of Riemannian manifolds with sectional curvature bound below collapsing to a compact Alexandrov space XX of dimension kk. Suppose that all but finitely many points of XX are (k,δ)(k,\delta)-strained and that the space of directions at each exceptional point contains k+1k+1 directions making obtuse angles with each other. We prove that MjM_j admits a structure of locally trivial fibration over XX for sufficiently large jj. The same is true for collapsing sequences of Alexandrov spaces such that the infimum of the volume of the spaces of directions is sufficiently large relative to δ\delta.

Keywords

Cite

@article{arxiv.2108.11030,
  title  = {Collapsing to Alexandrov spaces with isolated mild singularities},
  author = {Tadashi Fujioka},
  journal= {arXiv preprint arXiv:2108.11030},
  year   = {2023}
}

Comments

Added a simple proof of Theorem 1.1