Results 21 to 30 of about 207 (126)
A New Characterization of Totally Umbilical Hypersurfaces in de Sitter Space
Advances in Pure Mathematics, 2014 It is shown that a compact spacelike hypersurface which is contained in the chronological future (or past) of an equator of de Sitter space is a totally umbilical round sphere if the kth mean curvature function Hk is a linear combination of Hk+1,…, Hn. This is a new angle to characterize round spheres.
Linfen Cao, Guodong Xu, Zhaohui Dai
exaly +3 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
Integral inequalities for closed linear Weingarten submanifolds in the product spaces [PDF]
Anais da Academia Brasileira de Ciências, 2023 An integral inequality for closed linear Weingarten -submanifolds with parallel normalized mean curvature vector field (pnmc lw-submanifolds) in the product spaces ( ) × ℝ, > ≥ 4, where ( ) is a space form of constant sectional ...
FÁBIO R. DOS SANTOS +2 more
doaj +1 more source
Screen Semi-Invariant Lightlike Hypersurfaces on Hermite-Like Manifolds
Journal of New Theory, 2023 Hermite-like manifolds, which admit two different, almost complex structures, can be considered a general concept of Hermitian manifolds. Factoring in the effects of these two complex structures on the radical, screen, and transversal spaces, a new ...
Ömer Aksu, Mehmet Gülbahar
doaj +1 more source
Some New Results on Trans‐Sasakian Manifolds
Journal of Mathematics, Volume 2022, Issue 1, 2022., 2022 In this paper, we classify trans‐Sasakian manifolds which are realized as real hypersurfaces in a complex space form. We also investigate trans‐Sasakian manifolds whose Reeb vector fields are harmonic‐Killing. The above results bring some new characterizations for the property of trans‐Sasakian 3‐manifolds.
Lei Wang, Yan Zhao, Antonio Masiello
wiley +1 more source
CONFORMAL VECTOR FIELDS AND TOTALLY UMBILIC HYPERSURFACES [PDF]
Bulletin of the Korean Mathematical Society, 2002 Let \((M^n,g)\), \(n\geq 2\), be a connected semi-Riemannian hypersurface of a semi-Riemannian space form \((\overline{M}_k^{n+1}(\overline{c}),\overline{g})\) of signature \(k\). Assume that the ambient manifold carries a conformal vector field \(V\) such that the tangential part \((V|M^n)^T\) becomes a conformal vector field on the hypersurface. Then
Kim, Dong-Soo +3 more
openaire +1 more source
A Variational Problem and Classification Theorem for Extremal Hypersurfaces in the Space Form
Journal of Mathematics, Volume 2022, Issue 1, 2022., 2022 The classification of the isoparametric extremal hypersurfaces in the space form is obtained in this paper. We also derived the Euler‐Lagrange equation for extremal hypersurface and obtained Simons’ type integral inequality. When the integral equality holds, we can obtain the characteristics of isoparametric extremal hypersurfaces by using this ...
Yu-Chung Chang, Efthymios G. Tsionas
wiley +1 more source
Uniqueness of Complete Hypersurfaces in Weighted Riemannian Warped Products
Advances in Mathematical Physics, Volume 2021, Issue 1, 2021., 2021 In this paper, applying the weak maximum principle, we obtain the uniqueness results for the hypersurfaces under suitable geometric restrictions on the weighted mean curvature immersed in a weighted Riemannian warped product I×ρMfn whose fiber M has f‐parabolic universal covering. Furthermore, applications to the weighted hyperbolic space are given. In
Ning Zhang, Leopoldo Greco
wiley +1 more source
New Bernstein Type Results in Weighted Warped Products
Journal of Mathematics, Volume 2021, Issue 1, 2021., 2021 In this paper, we obtain new parametric uniqueness results for complete constant weighted mean curvature hypersurfaces under suitable geometric assumptions in weighted warped products. Furthermore, we also prove very general Bernstein type results for the constant mean curvature equation for entire graphs in these ambient spaces.
Ning Zhang, Yongqiang Fu
wiley +1 more source
Integral Formulas for Almost Product Manifolds and Foliations
Mathematics, 2022 Integral formulas are powerful tools used to obtain global results in geometry and analysis. The integral formulas for almost multi-product manifolds, foliations and multiply twisted products of Riemannian, metric-affine and sub-Riemannian manifolds, to ...
Vladimir Rovenski
doaj +1 more source