Riemannian submersions of brownian motions

In this paper it is shown that under some very mild and natural conditions the Riemannian submersion of Brownian motion is an autonomous diffusion with a drift proportional to the mean curvature of the fibres. Interpreting Brownian motion as the limit of a geodesic random walk enables us to give a natural explanation of this result     

双曲空间中完备子流形的特征值估计

研究了$(n+p)$维双曲空间$\mathbb{H}^{n+p}$中完备非紧子流形的第一特征值的上界.特别地,证明了$\mathbb{H}^{n+p}$中具有平行平均曲率向量$H$和无迹第二基本形式有限$L^q(q\geq n)$范数的完备子流形的第一特征值不超过$\frac{(n-1)^2(1-|H|^2)}{4}$,和$\mathbb{H}^{n+1}(n\leq5)$中具有常平均曲率向量$H$和无迹第二基本形式有限$L^q(2(1-\sqrt{\frac{2}{n}})相似文献   

K(a)hler流形上的单值化定理

本文研究了完备非紧且Ricci曲率正有界的n维K(a)hler流形上的单值化问题,利用Sobolev不等式,L2估计和Bézout估计和Gauss-Bonnet积分方法,得到了一个单值化定理,推广了流形为有限拓扑型的结果.     

Proper Submanifolds in Product Manifolds

The authors obtain various versions of the Omori-Yau's maximum principle on complete properly immersed submanifolds with controlled mean curvature in certain product manifolds,in complete Riemannian manifolds whose k-Ricci curvature has strong quadratic decay,and also obtain a maximum principle for mean curvature flow of complete manifolds with bounded mean curvature.Using the generalized maximum principle,an estimate on the mean curvature of properly immersed submanifolds with bounded projection in N1 in the product manifold N1 ×N2 is given.Other applications of the generalized maximum principle are also given.     

平坦外平行体的平均曲率积分的均值(英文)

本文研究了Rn中平坦的外平行体的平均曲率积分.利用积分几何的方法和凸体理论的相关知识,得到了这些平均曲率积分的均值.作为推论,我们得到了这些平均曲率积分所对应的均质积分的均值.     

Homotopy method for a mean curvature-based denoising model

Variational image denoising models based on regularization of gradients have been extensively studied. The total variation model by Rudin, Osher, and Fatemi (1992) [38] can preserve edges well but for images without edges (jumps), the solution to this model has the undesirable staircasing effect. To overcome this, mean curvature-based energy minimization models offer one approach for restoring both smooth (no edges) and nonsmooth (with edges) images. As such models lead to fourth order (instead of the usual second order) nonlinear partial differential equations, development of fast solvers is a challenging task. Previously stabilized fixed point methods and their associated multigrid methods were developed but the underlying operators must be regularized by a relatively large parameter. In this paper, we first present a fixed point curvature method for solving such equations and then propose a homotopy approach for varying the regularized parameter so that the Newton type method becomes applicable in a predictor-corrector framework. Numerical experiments show that both of our methods are able to maintain all important information in the image, and at the same time to filter out noise.     

4D neutral signature VSI and CSI spaces

In this paper we present a number of four-dimensional neutral signature exact solutions for which the polynomial scalar curvature invariants all vanish (VSI spaces) or are all constant (CSI spaces), which are of relevance in current theoretical physics.     

Regular quantizations and covering maps

Let $\tilde{M} \rightarrow MLet be a holomorphic (unbranched) covering map between two compact complex manifolds, with . We prove that if and M both admit regular K?hler forms and ω respectively then, up to homotheties, and (M, ω) are biholomorphically isometric. This work was supported by the M.I.U.R. Project “Geometric Properties of Real and Complex Manifolds”.     

Classification of negatively pinched manifolds with amenable fundamental groups

We give a diffeomorphism classification of pinched negatively curved manifolds with amenable fundamental groups, namely, they are precisely the Möbius band, and the products of R with the total spaces of flat vector bundles over closed infranilmanifolds.