arXiv research

The paper establishes estimates for convexity and injectivity radii in Riemannian manifolds.

The ratio of convexity radius over injectivity radius may be made arbitrarily small within the class of compact Riemannian manifolds of any fixed dimension at least two. This is proved using Gulliver's method of constructing manifolds with focal points but no conjugate points. The approach is suggested by a characteriz…

Estimates radius and volume of curved spaces with convex boundaries.

The paper proves an area inequality for metric balls in Riemannian manifolds.

Constructs geometric decompositions for thick hyperbolic 3-manifolds with bounded rank.

Sharp upper bounds on inscribed radius for metric spaces with convex boundary.

The paper proves bounds on curvature and injectivity radius for convex sums of Riemannian metrics.

In this article we pose the problem of existence and uniqueness of convex body for which the projection curvature radius function coincides with given function. We find a necessary and sufficient condition that ensures a positive answer to both questions and suggest an algorithm of construction of the body. Also we fin…

The paper confirms a conjecture about convex bodies and their properties.

The paper bounds bandwidth and focal radius for manifolds with positive isotropic curvature.

A version of a conjecture of McMullen is as follows: Given a hyperbolizable 3-manifold M with incompressible boundary, there exists a uniform constant K such that if N is a hyperbolic 3-manifold homeomorphic to the interior of M, then the injectivity radius based at points in the convex core of N is bounded above by K.…

A version of a conjecture of McMullen is as follows: Given a hyperbolizable 3-manifold M with incompressible boundary, there exists a uniform constant K such that if N is a hyperbolic 3-manifold homeomorphic to the interior of M, then the injectivity radius based at points in the convex core of N is bounded above by K.…

Through using the semidiameter (in connection to: the mean radius and surface radius) of a convex closed hypersurface in $\mathbb R^{n\ge 2}$ as an sharp upper bound of the variational $(1,n)\ni p$-capacity radius, this paper settles a restriction/variant of S.-T. Yau's \cite[Problem 59]{Yau} from the surface area to t…

Paper introduces robust market making using Wasserstein distance and entropy regularization.

Polynomial-time algorithm learns latent-state systems without spectral radius assumptions.

Study coning totally geodesic boundaries of hyperbolic manifolds.

This paper explores rigid properties of Alexandrov spaces with maximal radius.

In this paper, we mainly establish a Cheeger type finiteness theorem for Berwald manifolds. In order to do this, we study the injectivity radius and the convex radius of a Finsler manifold. A Cheeger type estimate on injectivity radii for Finsler manifolds is given and the existence of the center of mass of a Berwald m…

We consider a family of embedded, mean convex hypersurfaces which evolve by the mean curvature flow. It follows from general results of White that the inscribed radius at each point on the surface is at least $\frac{c}{H}$, where $c$ is a constant that depends only on the initial data. Andrews recently gave a new proof…

We obtain upper and lower bounds on the difference between the renormalized volume and the volume of the convex core of a convex cocompact hyperbolic 3-manifold which depend on the injectivity radius of the boundary of the universal cover of the convex core and the Euler characteristic of the boundary of the convex cor…

The paper establishes lower bounds on injectivity radius and constructs metrics with bounded geometry.

In a recent paper, Brendle proved that the inscribed radius of closed embedded mean convex hypersurfaces moving by mean curvature flow is at least 1/((1+δ)H) at all points with H > C(δ,M_0). In this note, we give a shorter proof of Brendle's estimate, and of a more general result for alpha-Andrews flows, based on our r…

Study lower bounds for connectivity of distance function level sets in convex sets.

Paper optimizes hyperparameters for high-dimensional regression models.

The paper studies area-preserving and length-preserving inverse curvature flow for planar curves with singularities.

The article considers the problem of existence and uniqueness of centrally symmetrical convex body for which the projection curvature radius function coincides with a given flag function. A necessary and sufficient condition is found that ensures a positive answer. An algorithm for construction the body in question is …

New algorithm reduces regret in stochastic bandit convex optimization.

A unique volume minimizer is found in a class of convex bodies.

Upper bounds for circumradius in Hadamard surfaces with curvature constraints.

Commentary on Busemann's foundational geometry papers.

Sharp inequalities on Riemannian manifolds for domain areas and volumes.

BMM algorithm improves convergence for nonconvex optimization problems.

We establish a second order smooth variational principle valid for functions defined on (possibly infinite-dimensional) Riemannian manifolds which are uniformly locally convex and have a strictly positive injectivity radius and bounded sectional curvature.

Study on spherical bodies of constant width on the unit sphere, proving bounds on their relative effective radius.

Develops a new method for robust risk measurement by averaging nearby payoffs.

Study circumcenters in Finsler unitary groups with optimal convexity bounds.

We present a novel, log-radius profile representation for convex curves and define a new operation for combining the shape features of curves. Unlike the standard, angle profile-based methods, this operation accurately combines the shape features in a visually intuitive manner. This method have implications in shape an…

Convex hypersurfaces evolve to spheres under a specific flow.

We consider a family of embedded, mean convex hypersurfaces in a Riemannian manifold which evolve by the mean curvature flow. We show that, given any number $T>0$ and any $δ>0$, we can find a constant $C_0$ with the following property: if $t \in [0,T)$ and $p$ is a point on $M_t$ where the curvature is greater than $C_…

In this article, we prove a Lichnerowicz estimate for a compact convex domain of a Kähler manifold whose Ricci curvature satisfies $\Ric \ge k$ for some constant $k>0$. When equality is achieved, the boundary of the domain is totally geodesic and there exists a nontrivial holomorphic vector field. We show that a ball o…

In a Riemannian manifold a regular convex domain is said to be $λ$-convex if its normal curvature at each point is greater than or equal to $λ$. In a Hadamard manifold, the asymptotic behaviour of the quotient $\vol(Ω(t))/\vol(\partialΩ(t))$ for a family of $λ$-convex domains $Ω(t)$ expanding over the whole space has b…

Given a hyperbolic domain, the nearest point retraction is a conformally natural homotopy equivalence from the domain to the boundary of the convex core of its complement. Marden and Markovic showed that if the domain is uniformly perfect, then there exists a conformally natural quasiconformal map which admits a bounde…

The paper studies how certain spacelike surfaces evolve over time in a specific space.

Gradient flow expands curves to round shapes.

Polyak step size GD reaches final radius of convergence after log iterations.

Study bounds changes in hyperbolic 3-manifold structures after drilling short geodesics.

We accelerate min-max optimization and apply it to minimal bounding sphere problems.

Let B be a thick spherical building equipped with its natural CAT(1) metric and let M be a proper, convex subset of B. If M is open or if M is a closed ball of radius pi/2, then the maximal subcomplex supported by the complement of M is spherical and non contractible.