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We study branched covering spaces in several contexts, proving that under suitable circumstances the cover satisfies the same upper curvature bounds as the base space. The first context is of a branched cover of an arbitrary metric space…

Differential Geometry · Mathematics 2007-05-23 Daniel Allcock

We relate the (non)existence of lower scalar curvature bounds to the existence of certain distance-decreasing maps. We also give a sufficient condition for the existence of a limiting scalar curvature measure in the backward limit of a…

Differential Geometry · Mathematics 2022-12-02 John Lott

We collect a few guesses on possible implications of a lower bound on the scalar curvature of a Riemannian manifold on the size and shape of this manifold.

Differential Geometry · Mathematics 2017-10-18 Misha Gromov

We analyze the limit of the p-form Laplacian under a collapse, with bounded sectional curvature and bounded diameter, to a smooth limit space. As an application, we characterize when the p-form Laplacian has small positive eigenvalues in a…

Differential Geometry · Mathematics 2007-05-23 John Lott

In this paper we present a self-contained combinatorial proof of the lower bound theorem for normal pseudomanifolds, including a treatment of the cases of equality in this theorem. We also discuss McMullen and Walkup's generalised lower…

Geometric Topology · Mathematics 2012-01-31 Bhaskar Bagchi , Basudeb Datta

In this paper, we study collapsed manifolds with boundary, where we assume a lower sectional curvature bound, two sides bounds on the second fundamental forms of boundaries and upper diameter bound. Our main concern is the case when inradii…

Differential Geometry · Mathematics 2019-12-11 Takao Yamaguchi , Zhilang Zhang

This paper is a survey on the structure of manifolds with a lower Ricci curvature bound.

Differential Geometry · Mathematics 2007-05-23 Guofang Wei

We study the rigidity of compact submanifolds of Riemannian manifolds of arbitrary codimension that satisfy a sharp pinching condition involving the norm of the second fundamental form and the mean curvature. Without assuming that the…

Differential Geometry · Mathematics 2026-03-25 Theodoros Vlachos

We prove a topological rigidity theorem for closed hypersurfaces of the Euclidean sphere and of an elliptic space form. It asserts that, under a lower bound hypothesis on the absolute value of the principal curvatures, the hypersurface is…

Differential Geometry · Mathematics 2018-09-28 Eduardo Longa , Jaime Ripoll

We develop a structure theory for RCD spaces with curvature bounded above in Alexandrov sense. In particular, we show that any such space is a topological manifold with boundary whose interior is equal to the set of regular points. Further…

Differential Geometry · Mathematics 2019-09-10 Vitali Kapovitch , Martin Kell , Christian Ketterer

We propose a definition of non-collapsed space with Ricci curvature bounded from below and we prove the versions of Colding's volume convergence theorem and of Cheeger-Colding dimension gap estimate for ${\sf RCD}$ spaces. In particular…

Metric Geometry · Mathematics 2025-06-24 Guido De Philippis , Nicola Gigli

Under an infinitesimal version of the Bishop-Gromov relative volume comparison condition for a measure on an Alexandrov space, we prove a topological splitting theorem of Cheeger-Gromoll type. As a corollary, we prove an isometric splitting…

Differential Geometry · Mathematics 2010-10-01 Kazuhiro Kuwae , Takashi Shioya

In this paper, we study the topology of topologically regular 4-dimensional open non-negatively curved Alexandrov spaces. These spaces occur naturally as the blow-up limits of compact Riemannian manifolds with lower curvature bound. These…

Differential Geometry · Mathematics 2010-10-12 Jian Ge

We prove generalized lower Ricci curvature bounds for warped products over complete Finsler manifolds. On the one hand our result covers a theorem of Bacher and Sturm concerning euclidean and spherical cones. On the other hand it can be…

Differential Geometry · Mathematics 2013-11-12 Christian Ketterer

Recently, in [49], a new definition for lower Ricci curvature bounds on Alexandrov spaces was introduced by the authors. In this article, we extend our research to summarize the geometric and analytic results under this Ricci condition. In…

Differential Geometry · Mathematics 2010-08-13 Hui-Chun Zhang , Xi-Ping Zhu

This is a technical paper, which is a continuation of math.DG/0211159. Here we construct Ricci flow with surgeries and verify most of the assertions, made in section 13 of that e-print; the exceptions are (1) the statement that manifolds…

Differential Geometry · Mathematics 2007-05-23 Grisha Perelman

We give a variational proof of the existence and uniqueness of a convex cap with the given upper boundary. The proof uses the concavity of the total scalar curvature functional on the space of generalized convex caps. As a byproduct, we…

Differential Geometry · Mathematics 2007-05-23 Ivan Izmestiev

Let $\{X_i\}$ be a sequence of compact $n$-dimensional Alexandrov spaces (e.g. Riemannian manifolds) with curvature uniformly bounded below which converges in the Gromov-Hausdorff sense to a compact Alexandrov space $X$. In an earlier paper…

Differential Geometry · Mathematics 2022-08-16 Semyon Alesker , Mikhail Katz , Roman Prosanov

This paper is devoted to the problem of prescribing the scalar curvature under zero boundary conditions. Using dynamical and topological methods involving the study of critical points at infinity of the associated variational problem, we…

Analysis of PDEs · Mathematics 2007-05-23 Mohamed Ben Ayed , Khalil El Mehdi , Mohameden Ould Ahmedou

This article is a sequel to the book `Ricci Flow and the Poincare Conjecture' by the same authors. Using the main results of that book we establish the Geometrization Conjecture for all compact, orientable three-manifolds following the…

Differential Geometry · Mathematics 2008-09-25 John Morgan , Gang Tian