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In this paper, we introduce a new notion for lower bounds of Ricci curvature on Alexandrov spaces, and extend Cheeger-Gromoll splitting theorem and Cheng's maximal diameter theorem to Alexandrov spaces under this Ricci curvature condition.

Differential Geometry · Mathematics 2010-09-28 Hui-Chun Zhang , Xi-Ping Zhu

Equipped with the L^2-distortion distance, the space "X" of all metric measure spaces (X,d,m) is proven to have nonnegative curvature in the sense of Alexandrov. Geodesics and tangent spaces are characterized in detail. Moreover, classes of…

Metric Geometry · Mathematics 2020-05-13 Karl-Theodor Sturm

Differentiable structure ensures that many of the basics of classical convex analysis extend naturally from Euclidean space to Riemannian manifolds. Without such structure, however, extensions are more challenging. Nonetheless, in…

Optimization and Control · Mathematics 2023-11-28 Adrian S. Lewis , Genaro López-Acedo , Adriana Nicolae

In this paper we give a new proof for an almost isometry theorem in Alexandrov spaces with curvature bounded below.

Differential Geometry · Mathematics 2010-06-29 Xiaole Su , Hongwei Sun , Yusheng Wang

We develop the theory of discrete-time gradient flows for convex functions on Alexandrov spaces with arbitrary upper or lower curvature bounds. We employ different resolvent maps in the upper and lower curvature bound cases to construct…

Metric Geometry · Mathematics 2017-01-18 Shin-ichi Ohta , Miklós Pálfia

The Gauss curvature measure of a pointed Euclidean convex body is a measure on the unit sphere which extends the notion of Gauss curvature to non-smooth bodies. Alexandrov's problem consists in finding a convex body with given curvature…

Metric Geometry · Mathematics 2019-03-18 Jérôme Bertrand , Philippe Castillon

In this paper we consider nonnegatively curved finite dimensional Alexandrov spaces with a non-collapsing condition, i.e., such that unit balls have volumes uniformly bounded from below away from zero. We study the relation between the…

Differential Geometry · Mathematics 2025-04-01 Gioacchino Antonelli , Marco Pozzetta

With the goal of solving optimisation problems on non-Riemannian manifolds, such as geometrical surfaces with sharp edges, we develop and prove the convergence of a forward-backward method in Alexandrov spaces with curvature bounded both…

Optimization and Control · Mathematics 2026-04-03 Heikki von Koch , Tuomo Valkonen

During the years 1940-1970, Alexandrov and the "Leningrad School" have investigated the geometry of singular surfaces in depth. The theory developed by this school is about topological surfaces with an intrinsic metric for which we can…

Differential Geometry · Mathematics 2022-01-11 Marc Troyanov

We will show that the quantitative maximal volume entropy rigidity holds on Alexandrov spaces. More precisely, given $N, D$, there exists $\epsilon(N, D)>0$, such that for $\epsilon<\epsilon(N, D)$, if $X$ is an $N$-dimensional Alexandrov…

Differential Geometry · Mathematics 2021-12-20 Lina Chen

We find conditions under which the pretangent spaces to general metric spaces have the nonpositive Aleksandrov curvature or nonnegative one. The infinitesimal structure of general metric cpaces with Busemann convex pretangent spaces is also…

Metric Geometry · Mathematics 2013-01-21 Viktoriia Bilet , Oleksiy Dovgoshey

We study three-dimensional Alexandrov spaces with a lower curvature bound, focusing on extending three classical results on three-dimensional manifolds: First, we show that a closed three-dimensional Alexandrov space of positive curvature,…

Differential Geometry · Mathematics 2014-04-03 Fernando Galaz-Garcia , Luis Guijarro

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

We classify positively curved Alexandrov spaces of dimension 4 with an isometric circle action up to equivariant homeomorphism, subject to a certain additional condition on the infinitesimal geometry near fixed points which we conjecture is…

Differential Geometry · Mathematics 2022-04-27 John Harvey , Catherine Searle

Alexandrov spaces are defined via axioms similar to those given by Euclid. The Alexandrov axioms replace certain equalities with inequalities. Depending on the signs of the inequalities, we obtain Alexandrov spaces with curvature bounded…

Differential Geometry · Mathematics 2023-06-13 Stephanie Alexander , Vitali Kapovitch , Anton Petrunin

In this paper, we study open complete metric spaces with non-negative curvature. Among other things, we establish an extension of Perelman's soul theorem for possibly singular spaces: "Let X be a complete, non-compact, finite dimensional…

Differential Geometry · Mathematics 2010-06-10 Jianguo Cao , Bo Dai , Jiaqiang Mei

We present a constructive proof of Alexandrov's theorem regarding the existence of a convex polytope with a given metric on the boundary. The polytope is obtained as a result of a certain deformation in the class of generalized convex…

Differential Geometry · Mathematics 2017-08-25 Alexander I. Bobenko , Ivan Izmestiev

In this note we prove the Borel Conjecture for closed, irreducible and sufficiently collapsed three-dimensional Alexandrov spaces. We also pose several questions related to characterization of fundamental groups of three-dimensional…

Metric Geometry · Mathematics 2020-11-26 Noé Bárcenas , Jesús Núñez-Zimbrón

In this paper we show that, in the definition of Alexandrov spaces with lower or upper curvature bound, the original conditions can be replaced with much weaker ones. For the purpose, we introduce `imaginary' comparison angles (and…

Differential Geometry · Mathematics 2023-08-30 Shengqi Hu , Xiaole Su , Yusheng Wang

We prove a reverse isoperimetric inequality for domains homeomorphic to a disc with the boundary of curvature bounded below lying in two-dimensional Alexandrov spaces of curvature $\geqslant c$. We also study the equality case.

Differential Geometry · Mathematics 2016-05-31 Alexander Borisenko