The study examines how average scalar curvature influences geometric properties of Riemannian manifolds.
problem Investigating the geometric properties of Riemannian manifolds influenced by average scalar curvature.
method Analyzing the conjugate radius, average area of geodesic spheres, average volume of metric balls, and total volume of closed manifolds.
result Improves the Bishop-Gromov estimate on the average volume of metric balls and proves monotone decreasing properties of certain geometric integrals.
The study finds the minimum average area ratio on hyperbolic manifolds and its relation to scalar curvature.
problem Finding the minimum average area ratio on hyperbolic manifolds.
method Analyzing the average area ratio and normalized total scalar curvature for hyperbolic n-manifolds.
result The average area ratio attains a local minimum of 1 at the hyperbolic metric.
A new method for averaging data on manifolds is proposed, offering simplicity and efficiency.
problem The difficulty of computing Fréchet means on manifolds, especially Stiefel and Grassmann.
method Proposed RL-barycenters, simpler arithmetic means projected onto the manifold.
result RL-barycenters yield simple yet effective means on Stiefel and Grassmann manifolds.
Local averaging accurately distills manifold structure from noisy data.
problem Tackles the challenge of uncovering manifold structure from noisy data.
method Two-round mini-batch local averaging method applied to noisy samples.
result Achieves accuracy bound of $d(\hat{\mathbf q}, \mathcal M) \leq σ\sqrt{d\left(1+\frac{κ\mathrm{diam}(\mathcal {M})}{\log(D)}
ight)}$.
The definition of the covariant space-time averaging scheme for the objects (tensors, geometric objects, etc.) on differentiable metric manifolds with a volume n-form, which has been proposed for the formulation of macroscopic gravity, is analyzed. An overview of the space-time averaging procedure in Minkowski spacetim…
The present research work proposes a new fast fixed-point averaging algorithm on the compact Stiefel manifold based on a mixed retraction/lifting pair. Numerical comparisons between fixed-point algorithms based on the proposed non-associated retraction/lifting map pair and two associated retraction/lifting pairs confir…
We present a geometric proof of the averaging theorem for perturbed dynamical systems on a Riemannian manifold, in the case where the flow of the unperturbed vector field is periodic and the S1-action associated to this vector field is not necessarily trivial. We generalize the averaging procedure \cite{A…
We give a procedure to ``average'' canonically C1-close Legendrian submanifolds of contact manifolds. As a corollary we obtain that, whenever a compact group action leaves a Legendrian submanifold almost invariant, there is an invariant Legendrian submanifold nearby.
Average intersection estimate for diffeomorphisms on manifolds.
problem Estimating geometric intersection numbers for diffeomorphisms on manifolds.
method Analyzing families of C1 diffeomorphisms and using volume products as an approximation. result The average geometric intersection number is approximately the product of volumes.
We give a construction to obtain canonically an ``isotropic average'' of given C1-close isotropic submanifolds of a symplectic manifold. To do so we use an improvement of Weinstein's submanifold averaging theorem (obtained in collaboration with H. Karcher) and apply ``Moser's trick''. We also present an application …
Proves a quantum invariant conjecture for specific three-manifolds.
problem Proving a conjecture about quantum invariants for certain three-manifolds.
method Gives an integral representation and resurgent asymptotic expansion for the average of GPPV invariants.
result Proves the Costantino--Geer--Patureau-Mirand invariant for negative definite plumbed three-manifolds.
Study irregular behavior of ball averages for non-amenable group actions on foliations.
problem Exploring irregular behavior of ball averages for non-amenable group actions.
method Introducing a new mechanism based on group structure to analyze irregular behavior.
result First examples of codimension one foliations with non-existent length averages.
Study mass transport in low-diffusivity using Lagrangian coordinates.
problem Mass preserving transport of passive tracers in low-diffusivity limit.
method Lagrangian coordinates, time-averaged diffusion equation, weighted manifold structure.
result Leading order asymptotics extend to dominant nontrivial singular value in low-diffusivity limit.
Minimal surfaces and average area ratio found to be maximized by hyperbolic metrics.
problem Finding sharp relations between minimal surface entropy and average area ratio.
method Ricci flow with surgery and invariant measures.
result Minimal surface entropy maximized by hyperbolic metrics among metrics with scalar curvature ≥ -6.
Discrete exterior calculus shows natural properties of wedge product and averaging.
problem Naturalness of discrete exterior calculus operations.
method Showed naturalness of discrete wedge product and averaging interpretation.
result Discrete wedge product is natural and equals Wilson's cochain product.
We describe an averaging procedure on a Dirac manifold, with respect to a class of compatible actions of a compact Lie group. Some averaging theorems on the existence of invariant realizations of Poisson structures around (singular) symplectic leaves are derived. We show that the construction of coupling Dirac structur…
New findings suggest no ensemble averaging for certain black hole observables.
problem Mystery in AdS/CFT correspondence regarding ensemble averaging of black hole amplitudes.
method Exploring sub-threshold observables in D=3 and proving novel results about hyperbolic geometry. result Connected solutions of Einstein's equations with disconnected boundary never contribute to sub-threshold observables.
In this paper, we motivate and define Φ-energy density, Φ-energy, Φ-harmonic maps and stable Φ-harmonic maps. Whereas harmonic maps or p-harmonic maps can be viewed as critical points of the integral of σ1 of a pull-back tensor, Φ-harmonic maps can be viewed as critical points of the integral of σ2 of…
Sharp gradient estimate for scalar curvature on 3-manifolds.
problem Control the rate of change of scalar curvature on 3-manifolds.
method Using a regularized distance function and Green's function, derive a sharp gradient estimate.
result Average of gradient of regularized distance is ≤ 1 on 3-manifolds with nonnegative scalar curvature.
Given a Finsler space (M,F) on a manifold M, the averaging method associates to Finslerian geometric objects affine geometric objects} living on M. In particular, a Riemannian metric is associated to the fundamental tensor g and an affine, torsion free connection is associated to the Chern-Rund connection. As an il…
Generalized Berwald manifolds are Finsler manifolds admitting linear connections such that the parallel transports preserve the Finslerian length of tangent vectors. By the fundamental result of the theory \cite{V5} such a linear connection must be metrical with respect to the averaged Riemannian metric given by integr…
Study on averaging geometric structures in Finsler spaces with Lorentzian signature.
problem Averaging geometric structures in Finsler spaces with Lorentzian signature.
method Definition of an average connection without using the timelike vector field.
result No direct relation between the two averaged objects.
Robustly computes intrinsic coordinates on point clouds using resampling and averaging.
problem Computing intrinsic coordinates on noisy or outlier-prone point clouds.
method Subsample data, vary hyperparameters, cluster candidate embeddings, identify representative embeddings, and average them using Procrustes analysis.
result Robust to noise and outliers, validated on synthetic and real data.
Magnetic Brunn-Minkowski inequalities on Riemannian manifolds
problem Establishing equivalence between Brunn-Minkowski inequalities and magnetic Ricci curvature
method Using magnetic geodesics
result Proving a sharp, undistorted Brunn-Minkowski inequality
In this paper we obtain three results concerning the geometry of complete noncompact positively curved Kähler manifolds at infinity. The first one states that the order of volume growth of a complete noncompact Kähler manifold with positive bisectional curvature is at least half of the real dimension (i.e., the complex…
Proves inequality linking function deviation to gradient norm on compact manifolds.
problem Analyzing coupled elliptic systems on compact manifolds.
method Develops a new Poincaré-Sobolev inequality with a density-free reference average.
result Poincaré constant depends on the density's gradient norm.
We classify, up to homeomorphisms, the closed simply-connected 4-manifolds that admit a Riemannian metric for which averages of pairs of sectional curvatures of orthogonal planes are positive.
We consider a problem of manifold estimation from noisy observations. Many manifold learning procedures locally approximate a manifold by a weighted average over a small neighborhood. However, in the presence of large noise, the assigned weights become so corrupted that the averaged estimate shows very poor performance…
In this thesis, we consider the suitability of using the charged cold fluid model in the description of ultra-relativistic beams. The method that we have used is the following. Firstly, the necessary notions of kinetic theory and differential geometry of second order differential equations are explained. Then an averag…
Optimal algorithms for Riemannian optimization with reduced complexity.
problem Stochastic optimization on Riemannian manifolds with limited data.
method Zeroth-order Riemannian Averaging Stochastic Approximation algorithms using Riemannian moving-average estimators and novel geometric conditions.
result Achieves optimal sample complexities for generating approximate first-order stationary solutions.
We define a C^1 distance between submanifolds of a riemannian manifold M and show that, if a compact submanifold N is not moved too much under the isometric action of a compact group G, there is a G-invariant submanifold C^1-close to N. The proof involves a procedure of averaging nearby submanifolds of riemannian manif…
The standard Bonnet-Myers theorem says that if the Ricci scalar of a Riemannian manifold is bounded below by a positive number, then the manifold is compact. Moreover, a bound of its diameter is pointed out. The theorem was extended to Finsler manifolds. In this paper we prove that if a certain condition on the average…
Let (M,g) be a complete non-compact Kähler manifold with non-negative and bounded holomorphic bisectional curvature. Extending our techniques developed in \cite{CT3}, we prove that the universal cover $\wt M$ of M is biholomorphic to $\ce^n$ provided either that (M,g) has average quadratic curvature decay, or $…
We compute curvatures of a three-manifold formed by a Weil-Petersson geodesic in Teichmuller space.
We extend average edge order results to normal 3-pseudomanifolds.
problem Determining the average edge order of normal 3-pseudomanifolds.
method Extending previous results on 3-manifolds to 3-pseudomanifolds with singularities.
result For a normal 3-pseudomanifold K, μ0(K)≥730, with equality if and only if K is a specific triangulation of RP2. The paper connects convex functions to p-subharmonic functions and proves their equivalence.
problem Understanding the relationship between convex functions and p-subharmonic functions.
method Average principle, variational methods, and PDE techniques.
result Convex functions on R^n are p-subharmonic for every p > 1.
The lowest eigenvalue of the Schrödinger operator −Δ+V on a compact Riemannian manifold without boundary is studied. We focus on the particularly subtle case of a sign changing potential with positive average.
Study differential operators on non-compact harmonic manifolds, finding conditions for radial fundamental solutions and dense heat-semigroups.
problem Conditions for differential operators on non-compact harmonic manifolds to have specific properties.
method Analyzing the algebra of differential operators, their commutation properties, and using geometric averages.
result Algebra of differential operators on non-compact harmonic manifolds has specific properties related to radial fundamental solutions and dense heat-semigroups.
The abstract discusses metrics with positive biorthogonal curvature on 5-manifolds.
problem Finding metrics with positive biorthogonal curvature on simply connected 5-manifolds.
method Using conformal deformation of Wilking's metric and results from Smale.
result Every closed simply connected 5-manifold admits a metric with strictly positive average sectional curvatures of orthogonal 2-planes.
The study uses Ricci flow to prove flatness of certain Riemannian manifolds.
problem Proving the flatness of Riemannian manifolds with specific curvature properties.
method Ricci flow approach, quantitative existence theory, curvature estimates, and regularization.
result Manifolds with non-negative curvature and specific decay rates are necessarily flat.
In this paper, by combining techniques from Ricci flow and algebraic geometry, we prove the following generalization of the classical uniformization theorem of Riemann surfaces. Given a complete noncompact complex two dimensional Kähler manifold M of positive and bounded holomorphic bisectional curvature, suppose its…
Stochastic variance reduction algorithms have recently become popular for minimizing the average of a large, but finite, number of loss functions. In this paper, we propose a novel Riemannian extension of the Euclidean stochastic variance reduced gradient algorithm (R-SVRG) to a compact manifold search space. To this e…
It is shown that given any link-manifold, there is an algorithm to decide if the manifold contains an embedded, essential planar surface; if it does, the algorithm will construct one. If a slope on the boundary of the link-manifold is given, there is an algorithm to determine if the slope bounds an embedded punctured-d…
Lower bounds on average normal curvature for submanifolds in Riemannian domains.
problem Finding bounds on the average normal curvature of submanifolds in Riemannian domains.
method Using an invariant measuring optimal n-trace convexity under unit-gradient normalization. result Lower bounds for the average normal curvature expressed in terms of an invariant.
New algorithm computes flag mean and median on flag manifolds.
problem Computing first order flag statistics on flag manifolds.
method Transformed problem to Stiefel manifold for optimization.
result Proved convergence and effectiveness of the flag-mean computation.
We write the Euler characteristic X(G) of a four dimensional finite simple geometric graph G=(V,E) in terms of the Euler characteristic X(G(w)) of two-dimensional geometric subgraphs G(w). The Euler curvature K(x) of a four dimensional graph satisfying the Gauss-Bonnet relation sum_x K(x) = X(G) can so be rewritten as …
We present an iterative technique for finding zeroes of vector fields on Riemannian manifolds. As a special case we obtain a ``nonlinear averaging algorithm'' that computes the centroid of a mass distribution supported in a set of small enough diameter D in a Riemannian manifold M. We estimate the convergence rate of o…
We consider the minimization of a function defined on a Riemannian manifold M accessible only through unbiased estimates of its gradients. We develop a geometric framework to transform a sequence of slowly converging iterates generated from stochastic gradient descent (SGD) on M to an averaged i…