Results 11 to 20 of about 17,898 (118)

Noninvariant Hypersurfaces of a Nearly Trans-Sasakian Manifolds

Journal of Mathematics, 2014
The present paper focuses on the study of noninvariant hypersurfaces of a nearly trans-Sasakian manifold equipped with (f,g,u,v,λ)-structure. Initially some properties of this structure have been discussed.
Satya Prakash Yadav, Shyam Kishor
doaj   +2 more sources

Totally umbilical hypersurfaces of a locally product Riemannian manifold

Kodai Mathematical Journal, 1967
It is well known that a totally umbilical hypersurface withnon-vanishing mean curvature of a Euclidean space is isometric with a sphere. Toprove this theorem we use, among others, the fact that in a Euclidean space themean curvature of a totally umbilical hypersurface is a constant.In more general Riemannian manifolds, however, there does not exist the
M. Okumura
openaire   +4 more sources

Ricci Solitons on Riemannian Hypersurfaces Generated by Torse-Forming Vector Fields in Riemannian and Lorentzian Manifolds

Axioms
In this paper, we examine torse-forming vector fields to characterize extrinsic spheres (that is, totally umbilical hypersurfaces with nonzero constant mean curvatures) in Riemannian and Lorentzian manifolds.
Norah Alshehri, Mohammed Guediri
doaj   +2 more sources

Spacelike Hypersurfaces in de Sitter Space

Axioms
A closed conformal vector field in de Sitter space S1n+1c¯ induces a vector field on a spacelike hypersurface M of S1n+1c¯, referred to as the induced vector field on M. This article investigates the characterization of compact spacelike hypersurfaces in
Yanlin Li, Mona Bin-Asfour, Kholoud Saad Albalawi, Mohammed Guediri   +3 more
doaj   +2 more sources

Impact of Ambient Conformal Vector Fields on Yamabe Solitons on Riemannian Hypersurfaces

Mathematics
We investigate Yamabe solitons on Riemannian hypersurfaces induced by conformal vector fields in Riemannian and Lorentzian manifolds, with an emphasis on the tangential component.
Norah Alshehri
doaj   +2 more sources

Gradient Ricci Solitons on Spacelike Hypersurfaces of Lorentzian Manifolds Admitting a Closed Conformal Timelike Vector Field

Mathematics
In this article, we investigate Ricci solitons occurring on spacelike hypersurfaces of Einstein Lorentzian manifolds. We give the necessary and sufficient conditions for a spacelike hypersurface of a Lorentzian manifold, equipped with a closed conformal ...
Norah Alshehri, Mohammed Guediri
doaj   +2 more sources

Classification and Existence of f-Biharmonic Hypersurfaces in Nonpositively Curved Conformally Flat Spaces

Axioms
We first study the f-biharmonicity of totally umbilical hypersurfaces in a Riemannian manifold of dimension n≥3 and prove that any totally umbilical proper f-biharmonic hypersurface without boundaries in a nonpositively curved manifold must be noncompact.
Ze-Ping Wang, Li-Hua Qin, Xue-Yi Chen
doaj   +2 more sources

Totally Umbilical Hypersurfaces of Lorentzian Reducible Spaces

Journal of Geometric Analysis
Abstract We investigate totally umbilical hypersurfaces in Lorentzian reducible spaces, focusing on their classification and geometric properties. We explore conditions for the existence of proper totally umbilical hypersurfaces in a $$(n+1)$$ (
Giovanni Calvaruso, Lorenzo Pellegrino, Calvaruso Giovanni   +2 more
exaly   +2 more sources

Generalized Robertson-Walker Space-Time Admitting Evolving Null Horizons Related to a Black Hole Event Horizon. [PDF]

Int Sch Res Notices, 2016
A new technique is used to study a family of time‐dependent null horizons, called “Evolving Null Horizons” (ENHs), of generalized Robertson‐Walker (GRW) space‐time (M¯,g¯) such that the metric g¯ satisfies a kinematic condition. This work is different from our early papers on the same issue where we used (1 + n)‐splitting space‐time but only some ...
Duggal KL.
europepmc   +2 more sources

Totally umbilical hypersurfaces of product spaces [PDF]

manuscripta mathematica, 2021
Given a Riemannian manifold $M,$ and an open interval $I\subset\mathbb{R},$ we characterize nontrivial totally umbilical hypersurfaces of the product $M\times I$ -- as well as of warped products $I\times_ωM$ -- as those which are local graphs built on isoparametric families of totally umbilical hypersurfaces of $M.$ By means of this characterization ...
Ronaldo F. de Lima, João Paulo dos Santos   +1 more
openaire   +2 more sources