Results 41 to 50 of about 207 (126)
Lightlike hypersurfaces of an indefinite Kaehler manifold of a quasi-constant curvature [PDF]
, 2019 summary:We study lightlike hypersurfaces $M$ of an indefinite Kaehler manifold $\bar {M}$ of quasi-constant curvature subject to the condition that the characteristic vector field $\zeta $ of $\bar {M}$ is tangent to $M$.
Lee, Jae Won, Jin, Dae Ho
core +1 more source
, 2021 International audienceThe Riemannian product M1(c1)×M2(c2), where Mi(ci) denotes the 2-dimensional space form of constant sectional curvature ci ∈ R, has two different Spin c structures carrying each a parallel spinor.
Nakad, Roger, Roth, Julien
core +1 more source
Totally umbilical hypersurfaces of manifolds admitting a unit Killing field [PDF]
Transactions of the American Mathematical Society, 2012 We prove that a Riemannian product of type M x R (where R denotes the Euclidean line) admits totally umbilical hypersurfaces if and only if M has locally the structure of a warped product and we give a complete description of the totally umbilical hypersurfaces in this case.
Souam, Rabah, Van der Veken, Joeri
openaire +2 more sources
Spacelike Hypersurfaces in Weighted Generalized Robertson‐Walker Space‐Times
Advances in Mathematical Physics, Volume 2018, Issue 1, 2018., 2018 Applying generalized maximum principle and weak maximum principle, we obtain several uniqueness results for spacelike hypersurfaces immersed in a weighted generalized Robertson‐Walker (GRW) space‐time under suitable geometric assumptions. Furthermore, we also study the special case when the ambient space is static and provide some results by using ...
Ximin Liu, Ning Zhang, Remi Léandre
wiley +1 more source
Advances in Mathematical Physics, Volume 2016, Issue 1, 2016., 2016 Based on general (1 + 3) threading of the spacetime (M, g), we obtain a new and simple splitting of both the Einstein field equations (EFE) and the conservation laws in (M, g). As an application, we obtain the splitting of EFE in an almost FLRW universe with energy‐momentum tensor of a perfect fluid.
Aurel Bejancu +2 more
wiley +1 more source
AxiomsWe 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 +1 more source
Timelike Tangent Developable Surfaces and Bonnet Surfaces
Abstract and Applied Analysis, Volume 2016, Issue 1, 2016., 2016 A criterion was given for a timelike surface to be a Bonnet surface in 3‐dimensional Minkowski space by Chen and Li, 1999. In this study, we obtain a necessary and sufficient condition for a timelike tangent developable surface to be a timelike Bonnet surface by the aid of this criterion.
Soley Ersoy, Kemal Eren, Chun-Gang Zhu
wiley +1 more source
A Class of Special Hypersurfaces in Real Space Forms
Journal of Function Spaces, Volume 2016, Issue 1, 2016., 2016 We define the generalized golden‐ and product‐shaped hypersurfaces in real space forms. A hypersurface M in real space forms Rn+1, Sn+1, and Hn+1 is isoparametric if it has constant principal curvatures. Based on the classification of isoparametric hypersurfaces, we obtain the whole families of the generalized golden‐ and product‐shaped hypersurfaces ...
Yan Zhao, Ximin Liu, Hugo Leiva
wiley +1 more source
On C^2 Umbilical Hypersurfaces
, 2022 We show by an elementary argument that the second fundamental form of a connected, totally umbilical hypersurface of class C2 is a constant multiple of the metric tensor. It follows that the hypersurface is smooth and it is either a piece of a hyperplane
carlo mantegazza
core +1 more source
On totally umbilical and minimal surfaces of the Lorentzian Heisenberg groups
Mathematische Nachrichten, Volume 298, Issue 6, Page 1922-1942, June 2025.Abstract This paper has manifold purposes. We first introduce a description of the Gauss map for submanifolds (both spacelike and timelike) of a Lorentzian ambient space and relate the conformality of the Gauss map of a surface to total umbilicity and minimality.
Giovanni Calvaruso +2 more
wiley +1 more source