Ricci tensor

The porous medium equation arises in different applications to model diffusive phenomena. In this paper, we obtain several gradient estimates for some porous medium type equations on smooth metric measure space with N-Bakry-Emery Ricci tensor bounded from below. In particular, we improve and generalize some current gradient estimates for the porous medium equations.

9p danhdanh27 07-01-2019 20 1   Download

In this paper, we study coisotropic submanifolds of a semi-Riemannian manifold. We investigate the integrability condition of the screen distribution and give a necessary and sufficient condition on Ricci tensor of a coisotropic submanifold to be symmetric.

18p danhdanh27 07-01-2019 20 1   Download

In this paper, we study slant submanifolds of a Kaehler product manifold. We show that an F-invariant slant submanifold of Kaehler product manifold is a product manifold. We also obtain some curvature inequalities in terms of scalar curvature and Ricci tensor.

13p danhdanh27 07-01-2019 21 1   Download

In this paper, the induced Ricci tensor and the extrinsic scalar curvature on lightlike submanifolds are obtained. This scalar quantity extend the result given by C. Atindogbe in. An example of extrinsic scalar curvature on one class of 2-degenerate manifolds is provided.

19p tuongvidanh 06-01-2019 14 1   Download

The object of the present paper is to introduce spacetimes with pseudosymmetric energymomentum tensor. In this paper at first we consider the relation R(X,Y)· T = f Q(g,T), that is, the energy-momentum tensor T of type (0,2) is pseudosymmetric. It is shown that in a general relativistic spacetime if the energy-momentum tensor is pseudosymmetric, then the spacetime is also Ricci pseudosymmetric and the converse is also true.

8p thuyliebe 08-10-2018 13 0   Download

We study the problem of conformally deforming a metric to a prescribed symmetric function of the eigenvalues of the Ricci tensor. We prove an existence theorem for a wide class of symmetric functions on manifolds with positive Ricci curvature, provided the conformal class admits an admissible metric. 1. Introduction Let (M n , g) be a smooth, closed Riemannian manifold of dimension n.

58p noel_noel 17-01-2013 52 6   Download