Study describes limits of surfaces in a mathematical space.
problem Understanding limits of surfaces in mathematical spaces.
method Completely described Gromov-Hausdorff closure of surfaces.
result Completely described the closure of surfaces.
New theorem on flat tori stability using harmonic maps and Ricci flow.
problem Stability of flat tori under Ricci and scalar curvature bounds.
method Harmonic map heat flow, Ricci flow, and RCD theories.
result Gromov-Hausdorff stability theorem for flat 3-tori.
Close to complex projective spaces, Ricci shrinkers are rigid.
problem Rigidity of complex projective spaces in Ricci shrinkers.
method Proving isometry using Gromov-Hausdorff distance.
result Ricci shrinkers close to (CPN,gFS) are isometric to (CPN,gFS). A theorem of Anderson and Bando-Kasue-Nakajima from 1989 states that to compactify the set of normalized Einstein metrics with a lower bound on the volume and an upper bound on the diameter in the Gromov-Hausdorff sense, one has to add singular spaces called Einstein orbifolds, and the singularities form as blow-downs …
We develop a new approach to, and small extension of, results of Cheeger, Colding and Tian concerning the Lk/2 norm of the curvature of a Riemannian manifold Gromov-Hausdorff close to a codimension k singularity.
We show that for a noncollapsing sequence of closed, connected, oriented Riemannian manifolds with Ricci curvature uniformly bounded from below and diameter uniformly bounded above, Gromov-Hausdorff convergence essentially agrees with intrinsic flat convergence.
Study flat manifolds' collapsed limits as flat orbifolds.
problem Understanding collapsed limits of flat manifolds.
method Analyzing totally geodesic foliations and Gromov-Hausdorff limits.
result Identify collapsed limits as flat orbifolds and provide criteria for singularity.
We show that a complete Riemannian manifold of dimension n with $\Ric\geq n{-}1$ and its n-st eigenvalue close to n is both Gromov-Hausdorff close and diffeomorphic to the standard sphere. This extends, in an optimal way, a result of P. Petersen. We also show that a manifold with $\Ric\geq n{-}1$ and volume close…
This manuscript studies manifolds-with-boundary collapsing in the Gromov-Hausdorff topology. The main aim is an understanding of the relationship of the topology and geometry of a limiting sequence of manifolds-with-boundary to that of a limit space, which is presumed to be without geodesic terminals. The main result e…
We show that for n dimensional manifolds whose the Ricci curvature is greater or equal to n-1 and for k in {1,...,n+1}, the k-th eigenvalue for the Laplacian is close to n if and only if the manifold contains a subset which is Gromov-Hausdorff close to the unit sphere of dimension k-1. For k=n+1, this gives a new proof…
Study G-H limits of surfaces with boundary, focusing on same Euler characteristic.
problem Investigate Gromov-Hausdorff limits of compact surfaces with boundary.
method Focus on surfaces with same Euler characteristic, build on previous work on closed surfaces.
result Complete description and topological properties of limit spaces.
Let M be a compact Riemannian manifold with boundary. We show that M is Gromov-Hausdorff close to a convex Euclidean region D of the same dimension if the boundary distance function of M is C1-close to that of D. More generally, we prove the same result under the assumptions that the boundary distance func…
Study shows closed manifolds close to flat tori under Kato Ricci curvature bounds.
problem Stability of closed Riemannian manifolds with small Kato Ricci curvature.
method Geometric and diffeomorphic stability results for manifolds with small Kato Ricci curvature.
result Closed manifolds with small Kato Ricci curvature are close to flat tori and diffeomorphic to tori.
In the present paper, we determine the topologies of three-dimensional closed Alexandrov spaces which converge to lower dimensional spaces in the Gromov-Hausdorff topology.
Compactness theorem for manifolds with scalar curvature and entropy bounds.
problem Understanding the structure of manifolds with specific curvature and entropy bounds.
method Using volume upper bounds to prove Gromov-Hausdorff closeness to Euclidean balls.
result Unit balls in such manifolds are bi-Hölder and bi-W1,p homeomorphic to Euclidean balls. Proves stability of convex disks close to round caps.
problem Stability of convex disks with positive curvature and strictly convex boundary.
method Compactness result for a Liouville-type PDE problem.
result Proves stability for a theorem of F. Hang and X. Wang.
This paper constructs a function on Gromov-Hausdorff limits of 2-surfaces with curvature constraints.
problem Understanding geometric properties of limits of surfaces with curvature constraints.
method Construction of an integer-valued function on the limit space.
result Existence and classification of functions on Gromov-Hausdorff limits of 2-surfaces.
The study shows almost maximal volume entropy rigidity for certain manifolds with integral Ricci curvature.
problem Volume entropy rigidity for manifolds with lower integral Ricci curvature bound.
method Analyzing manifolds with specific integral Ricci curvature bounds, diameter, and volume entropy.
result The universal cover of the manifold is close to a hyperbolic space form under certain conditions.
Proves torus sequences can't collapse to intervals under curvature bounds.
problem Proving torus sequences can't collapse to intervals under curvature bounds.
method Contradiction proof using Yamaguchi fibration theorem and covers.
result Proves tori can't collapse to intervals under curvature constraints.
Let (Y,d) be a Gromov-Hausdorff limit of closed shrinking Ricci solitons with uniformly upper bounded diameter and lower bounded volume. We prove that off a closed subset of codimension at least 2, Y is a smooth manifold satisfying a shrinking Ricci soliton equation.
This paper examines limits of Riemannian 2-manifolds with bounded curvature.
problem Understanding the limits of Riemannian 2-manifolds with bounded curvature.
method Uniform semi-locally 1-connected sequences of closed connected Riemannian 2-manifolds with bounded total absolute curvature.
result Description of Gromov-Hausdorff limits of the sequences.
Study the topology of Ricci limit spaces using Gromov-Hausdorff limits.
problem Topology of Ricci limit spaces.
method Gromov-Hausdorff limits, slice theorem for isometric pseudo-group actions, uniform diameter bounds.
result Established semi-locally simply connected property and described universal cover.
The study proves compactness and structure of Ricci flow limits.
problem Understanding the structure of Ricci flow limits.
method Weak compactness theorem and structure theory development.
result Ricci flow limit spaces have a regular part with smooth convergence and a singular set of high codimension.
Study shows different fundamental groups for manifolds with same limit.
problem Understanding fundamental groups of manifolds with non-negative Ricci curvature.
method Constructed sequences of manifolds with specific properties.
result Found manifolds with same limit but different fundamental groups.
Space of hyperbolic surfaces is path-connected.
problem Topology of hyperbolic surfaces and their subspaces.
method Constructing paths using Fenchel-Nielsen coordinates and shrinking curves.
result Path-connectivity of the space of hyperbolic surfaces.
Gromov-Hausdorff convergence of time-slices of singular Ricci flows
problem Gromov-Hausdorff convergence of time-slices of singular Ricci flows
method Completion of singular Ricci flow with respect to a natural spacetime distance
result Gromov-Hausdorff convergence at the first singular time
Let (Y,d) be a Gromov-Hausdorff limit of n-dimensional closed shrinking Kähler-Ricci solitons with uniformly bounded volumes and Futaki invariants. We prove that off a closed subset of codimension at least 4, Y is a smooth manifold satisfying a shrinking Kähler-Ricci soliton equation. A similar convergence result …
The paper characterizes limits of manifolds using Gromov-Hausdorff metric.
problem Characterizing limits of generalized manifolds using Gromov-Hausdorff metric.
method Using Gromov-Hausdorff metric dG, the paper proves that manifold-like generalized n-manifolds are limits of topological n-manifolds under certain conditions. result Manifold-like generalized n-manifolds are limits of topological n-manifolds under specific conditions. The paper proves stability in compact finite dimensional Alexandrov spaces using equivariant Gromov--Hausdorff convergence.
problem Stability in compact finite dimensional Alexandrov spaces.
method Equivariant Gromov--Hausdorff convergence and almost commutative diagrams.
result Stability result in compact finite dimensional Alexandrov spaces.
New examples show strong Kato limits can be branching and not satisfy known conditions.
problem Exploring the boundaries of strong Kato limits and their properties.
method Constructing specific examples of non-collapsed strong Kato limits.
result Found examples of strong Kato limits that are branching and do not satisfy CD(K,∞) or MCP(K,N) conditions. The paper proves topological stability between RCD spaces and Riemannian manifolds.
problem Proving topological stability between RCD spaces and Riemannian manifolds.
method Using Gromov-Hausdorff distance and regular homeomorphisms, the paper constructs a map between spaces.
result There exists a regular homeomorphism between RCD spaces and Riemannian manifolds under certain conditions.
Study shows stability of Schrödinger operator spectral data on a manifold.
problem Determining a manifold and potential function from spectral data.
method Approximation of spectral data on a subset to determine manifold and potential.
result Quantitative stability estimate for Schrödinger operator inverse problem.
Study Gromov-Hausdorff convergence of metric pairs and tuples.
problem Understanding convergence in metric spaces.
method Prove equivalence of definitions, embedding, completeness, and compactness theorems.
result Relative version of Fukaya's theorem and finiteness theorem for stratified spaces.
Round cylinders are rigid in Ricci shrinkers close to the standard product.
problem Proving rigidity of round cylinders in Ricci shrinkers.
method Proving isometry using pointed-Gromov-Hausdorff topology.
result Ricci shrinkers close to Sn−1imesR are isometric to Sn−1imesR. Quantitative rigidity theorem for Alexandrov spaces with curvature bounds.
problem Quantifying rigidity in Alexandrov spaces with curvature constraints.
method Using Gromov-Hausdorff distance and properties of Alexandrov spaces.
result Alexandrov spaces with curvature bounds are close to hyperbolic manifolds.
In this paper we prove that generic small partial smoothings of Kahler-Einstein (KE) Del Pezzo orbifolds with only nodal singularities, and with no non-zero holomorphic vector fields, admit orbifold KE metrics which are close in the Gromov-Hausdorff sense to the original KE metric.
Study uses equivariant topology to measure distances between G metric spaces.
problem Measuring distances between G metric spaces.
method Equivariant topology methods to derive lower bounds.
result Sharp bounds on Gromov Hausdorff distance between spheres.
Rigidity and almost rigidity of Sobolev inequalities on compact spaces with lower Ricci curvature bounds.
problem Characterizing and proving rigidity and almost rigidity of Sobolev inequalities on compact spaces with lower Ricci curvature bounds.
method Analysis of Riemannian manifolds and metric measure spaces with synthetic lower Ricci curvature bounds, using concentration compactness and Polya-Szego inequalities.
result Closed Riemannian manifolds with optimal Sobolev constant are isometric to the sphere, and almost equality implies close measure Gromov-Hausdorff convergence to a spherical suspension.
We construct for every finite-dimensional Alexandrov space A and every point p∈A a 2-convex function fp in a small neighborhood around p, which approximates distp2 up to second order. Moreover, the function fp can be lifted to Gromov-Hausdorff close Alexandrov spaces of the same dim…
Study shows intrinsic timed Hausdorff convergence leads to Gromov-Hausdorff and big bang convergence.
problem Distance between Lorentzian manifolds.
method Intrinsic timed Hausdorff convergence.
result Intrinsic timed Hausdorff convergence implies Gromov-Hausdorff and big bang convergence.
Stability of Wasserstein spaces under various convergence types.
problem Stability and finiteness of Wasserstein spaces over singular and non-singular spaces.
method Gromov--Hausdorff convergence and equivariant Gromov--Hausdorff convergence.
result Analogue of Perelman's stability theorem on Wasserstein spaces.
Study Ricci flow on spaces with conical singularities, proving existence and curvature estimates.
problem Analyzing Ricci flow on spaces with conical singularities.
method Existence proof for Ricci flow, curvature estimates, and tangent flow analysis.
result Existence of a solution to Ricci flow for a specific class of spaces.
We study topological properties of the Gromov-Hausdorff metric on the set of isometry classes of nonnegatively curved 2-spheres.
Gromov-Hausdorff distances measure shape difference between the objects representable as compact metric spaces, e.g. point clouds, manifolds, or graphs. Computing any Gromov-Hausdorff distance is equivalent to solving an NP-Hard optimization problem, deeming the notion impractical for applications. In this paper we pro…
The paper connects geometric and topological concepts to bound distances between metric spaces.
problem Bounding distances between metric spaces using Gromov-Hausdorff distance.
method Using Borsuk-Ulam theorems and Vietoris-Rips complexes, the paper obstructs the existence of certain continuous maps between complexes to bound discontinuities of functions.
result The paper provides new bounds on Gromov-Hausdorff distances between spheres of different dimensions.
The paper constructs metrics on tori with Ricci bounds and shows Gromov-Hausdorff limits are not always manifolds.
problem Understanding the Gromov-Hausdorff limits of tori with Ricci conditions.
method Constructing metrics on Rn and analyzing their limits. result The Gromov-Hausdorff limit of tori with Ricci bounds is not always a topological manifold.
Study shows dimension constraints for isometry groups in non-collapsed Riemannian manifolds.
problem Dimension constraints for isometry groups in non-collapsed Riemannian manifolds.
method Equivariant Gromov--Hausdorff convergence and lower Ricci curvature bounds.
result Dimension of isometry group is at least the limit superior of dimensions of subgroups.
Flow analysis leads to metric completion in Kähler geometry.
problem Analyzing Kähler-Ricci flows on compact manifolds.
method Normalized Kähler-Ricci flow convergence to Gromov-Hausdorff limits.
result Metric completion of twisted Kähler-Einstein metric.