arXiv research

We refine a metric bunching estimate for pinched manifolds.

Study pinching constants for Kähler manifolds with positive curvature.

Flat Yang-Mills connections on pinched manifolds.

Proves CLT for Brownian paths on pinched negative curvature manifolds.

Sharp pinching conditions restrict the geometry and topology of submanifolds.

The study finds optimal curvature pinching in Heintze groups.

In this paper, we proved a compactness result about Riemannian manifolds with an arbitrary pointwisely pinched Ricci curvature tensor.

The paper constructs a new metric on Kähler manifolds.

Alternative proof of flatness for Ricci-pinched 3-manifolds.

We show that a compact Riemannian manifold with weakly 1/4-pinched sectional curvatures is either locally symmetric or diffeomorphic to a space form.

In this note we consider versions of both Ricci and sectional curvature pinching for Riemannian manifold with density. In the Ricci curvature case the main result implies a diameter estimate that is new even for compact shrinking Ricci solitons. In the case of sectional curvature we prove a new sphere theorem.

We show that the 2-jet bundle of local Riemannian metrics on an arbitrary differentiable manifold admits a section which pointwise fulfills the curvature relation sec(g)=a for any real number a. It follows by Gromov's h-principle for open, invariant differential relations that every noncompact differentiable manifold c…

Study pinches Weyl curvature on 4-manifolds, proving anti-self-duality.

New findings on curvature and null spaces of Laplacians.

A sharp vanishing theorem for the $L^p$ cohomology torsion of Riemannian manifolds with pinched negative curvature is given. It follows that certain negatively curved homogeneous spaces cannot be quasiisometric to better pinched manifolds.

We prove that some Riemannian manifolds with boundary under an explicit integral pinching are spherical space forms. Precisely, we show that 3-dimensional Riemannian manifolds with totally geodesic boundary, positive scalar curvature and an explicit integral pinching between the $L^2$-norm of their scalar curvature and…

Given a closed contact 3-manifold with a compatible Riemannian metric, we show that if the sectional curvature is 1/4-pinched, then the contact structure is universally tight. This result improves the Contact Sphere Theorem in [EKM12], where a 4/9-pinching constant was imposed. Some tightness results on positively curv…

The paper proves conditions for a manifold to be homeomorphic to a spherical space form.

Study high codimension mean curvature flow in Riemannian manifolds, proving limiting flow in Euclidean space.

Study expands classical harmonic function results to Riemannian manifolds.

Study sharp geometric and topological properties of pinched 4D submanifolds.

New progress on frame flow ergodicity for nearly pinched manifolds.

We prove that all smooth sphere bundles that admit fiberwise 1/4-pinched metrics are induced bundles of vector bundles, so their structure groups reduce from the diffeomorphism group of the sphere to the orthogonal group. This result implies the existence of many smooth n-sphere bundles over a k-sphere that do not supp…

Study pinches eigenvalues and curvatures of convex hypersurfaces to make them nearly geodesic spheres.

The paper studies the ergodicity of frame flow on even-dimensional manifolds.

We prove that the space of complete, finite volume, pinched negatively curved Riemannian metrics on a smooth high-dimensional manifold is either empty or it is highly non-connected, provided their behavior at infinity is similar.

In a previous paper, we proved a number of optimal rigidity results for Riemannian manifolds of dimension greater than four whose curvature satisfy an integral pinching. In this article, we use the same integral Bochner technique to extend the results in dimension three. Then, by using the classification of closed thre…

The abstract discusses compactness of manifolds with pinched Ricci curvature.

We give an estimate of the first eigenvalue of the Laplace operator on a complete noncompact stable minimal hypersurface $M$ in a complete simply connected Riemannian manifold with pinched negative sectional curvature. In the same ambient space, we prove that if a complete minimal hypersurface $M$ has sufficiently smal…

Estimates eigenvalue for manifolds with specific forms under certain conditions.

Minimal submanifolds are stable in certain conformal spheres.

A 3-manifold's Ricci pinching condition implies it's flat if it has Euclidean volume growth.

We prove a non-vanishing result for the $L_{q,p}$-cohomology of complete simply-connected Riemannian manifolds with pinched negative curvature.

We derive various pinching results for small Dirac eigenvalues using the classification of $\text{spin}^c$ and spin manifolds admitting nontrivial Killing spinors. For this, we introduce a notion of convergence for $\text{spin}^c$ manifolds which involves a general study on convergence of Riemannian manifolds with a pr…

Study shows how certain curved bundles reduce their structure group.

We consider a complete noncompact Riemannian manifold M and give conditions on a compact submanifold K of M so that the outward normal exponential map off of the boundary of K is a diffeomorphism onto M\K. We use this to compactify M and show that pinched negative sectional curvature outside K implies M has a compactif…

Let (X,g) be a metrically complete, simply connected Riemannian manifold with bounded geometry and pinched negative curvature, i.e. there are constants a>b>0 such that -a^2<K<-b^2 for all sectional curvatures K. Here bounded geometry is used in the sense that all covariant derivatives of the Riemannian curvature tensor…

Yamabe flow proves compactness of certain locally conformally flat manifolds with positive Ricci curvature.

The goal of this article is to study the pinching problem proposed by S.-T. Yau in 1990 replacing sectional curvature by one weaker condition on biorthogonal curvature. Moreover, we classify 4-dimensional compact oriented Riemannian manifolds with nonnegative biorthogonal curvature. In particular, we obtain a partial a…

The study pinches conditions for constant mean curvature surfaces in convex 3-manifolds.

Sphere theorems extended to Riemannian foliations with new results on curvature and leaf spaces.

Study approximates product of spheres using Laplacian eigenvalues.

We study Fredholm properties and index formulas for Dirac operators over complete Riemannian manifolds with straight ends. An important class of examples of such manifolds are complete Riemannian manifolds with pinched negative sectional curvature and finite volume.

New proof shows 3-manifolds with specific curvature properties are either flat or compact.

Let (M,g_0) be a compact Riemannian manifold with pointwise 1/4-pinched sectional curvatures. We show that the Ricci flow deforms g_0 to a constant curvature metric. The proof uses the fact, also established in this paper, that positive isotropic curvature is preserved by the Ricci flow in all dimensions. We also rely …

$L^p$-cohomology of rank one symmetric spaces of noncompact type is shown to be Hausdorff for values of $p$ where this does not follow from curvature pinching. Using the multiplicative structure on $L^p$-cohomology, it is shown that no simply connected Riemannian manifold with strictly -1/4-pinched sectional curvature …

In early 80's M.Gromov showed that there exists a constant $ε$ such that any compact Riemannian manifold $M^n$ with $|K|_{M^n} \cdot diam^2(M^n) \leq ε$ can be finitely covered by a nilmanifold. The present paper illustrates by an explicit example that the pinching constant $ε$ depends on the dimension $n$ of the manif…

The gradient shrinking $ρ$-Einstein soliton is a triple $(M^n,g,f)$ such that $R_{ij}+f_{ij}=(ρR+λ) g_{ij},$ where $(M^n,g)$ is a Riemannian manifold, $λ>0, ρ\in\mathbb{R}\setminus\{0\}$ and $f$ is the potential function on $M^n$. In this paper, using algebraic curvature estimates and the Yamabe-Sobolev inequality, w…