Géométrie différentielle du 2ème ordre, semi-martingales et équations différentielles stochastiques sur une variété différentielle
We study stochastically perturbed non-holonomic systems from a geometric point of view. In this setting, it turns out that the probabilistic properties of the perturbed system are intimately linked to the geometry of the constraint distribution. For -Chaplygin systems, this yields a stochastic criterion for the existence of a smooth preserved measure. As an application of our results we consider the motion planning problem for the noisy two-wheeled robot and the noisy snakeboard.
On sait depuis Maslov, Arnold, etc... associer à presque tout germe de variété lagrangienne ou legendrienne lisse une classe de fonctions oscillantes qui sous des hypothèses génériques à la Thom fournissent des modèles universels pour le comportement d’une onde lumineuse au voisinage de la caustique.Le présent article étend cette construction à une classe de situations où la variété caractéristique est un germe singulier (union de composantes lisses), qui peut néanmoins être stable en ce sens que...
In this paper, we will study global well-posedness for the cubic defocusing nonlinear Schrödinger equations on the compact Riemannian manifold without boundary, below the energy space, i.e. , under some bilinear Strichartz assumption. We will find some , such that the solution is global for .
Let be a complete noncompact Riemannian manifold. We consider gradient estimates on positive solutions to the following nonlinear equation in , where , are two real constants and , is a smooth real valued function on and . When is finite and the -Bakry-Emery Ricci tensor is bounded from below, we obtain a gradient estimate for positive solutions of the above equation. Moreover, under the assumption that -Bakry-Emery Ricci tensor is bounded from below and is bounded from above,...
We prove gradient estimates for hypersurfaces in the hyperbolic space Hn+1, expanding by negative powers of a certain class of homogeneous curvature functions F. We obtain optimal gradient estimates for hypersurfaces evolving by certain powers p > 1 of F-1 and smooth convergence of the properly rescaled hypersurfaces. In particular, the full convergence result holds for the inverse Gauss curvature flow of surfaces without any further pinching condition besides convexity of the initial hypersurface....
In this paper, we consider gradient estimates on complete noncompact Riemannian manifolds for the following general heat equation where is a constant and is a differentiable function defined on . We suppose that the Bakry-Émery curvature and the -dimensional Bakry-Émery curvature are bounded from below, respectively. Then we obtain the gradient estimate of Li-Yau type for the above general heat equation. Our results generalize the work of Huang-Ma ([4]) and Y. Li ([6]), recently.