Results 41 to 50 of about 179 (133)

On the Splitting of the Einstein Field Equations with respect to General (1 + 3) Threading of Spacetime

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, Hani Reda Farran, Eugen Radu   +2 more
wiley   +1 more source

Totally umbilical CMC hypersurfaces of a conformally recurrent manifold

, 2001
It has been shown that a non-degenerate totally umbilical constant mean curvature hypersurface of a conformally recurrent pseudo Riemannian manifold is conformally ...
Sharma, R., Tarafdar, M.
core   +1 more source

Characterization of hypersurfaces in four dimensional product spaces via two different Spin^c structures

, 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

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

A short note on $f$-biharmonic hypersurfaces [PDF]

, 2020
summary:In the present paper we give some properties of $f$-biharmonic hypersurfaces in real space forms. By using the $f$-biharmonic equation for a hypersurface of a Riemannian manifold, we characterize the $f$-biharmonicity of constant mean curvature ...
Blaga, Adara M., Perktaş, Selcen Y., Acet, Bilal E.   +2 more
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, Marco Castrillón‐Lopez, Lorenzo Pellegrino   +2 more
wiley   +1 more source

Conformal Vector Fields and Null Hypersurfaces [PDF]

, 2022
We give conditions for a conformal vector field to be tangent to a null hypersurface. We particularize to two important cases: a Killing vector field and a closed and conformal vector field.
Olea, Benjamín, Atindogbé, Cyriaque
core   +1 more source

Multiplicative rectifying submanifolds of multiplicative Euclidean space

Mathematical Methods in the Applied Sciences, Volume 48, Issue 1, Page 329-339, 15 January 2025.
In this paper, we initiate the study of the multiplicative Euclidean submanifolds, exhibiting the multiplicative counterparts of the Gauss–Weingarten formulas. Some particular types such as multiplicative conic, spherical, and totally geodesic submanifolds are analyzed.
Muhittin Evren Aydin, Aykut Has, Beyhan Yilmaz   +2 more
wiley   +1 more source

Lightlike Hypersurfaces of Indefinite Generalized Sasakian Space Forms

Journal of Applied Mathematics, Volume 2015, Issue 1, 2015., 2015
We study lightlike hypersurfaces M of an indefinite generalized Sasakian space form M-(f1,f2,f3), with indefinite trans‐Sasakian structure of type (α, β), subject to the condition that the structure vector field of M- is tangent to M. First we study the general theory for lightlike hypersurfaces of indefinite trans‐Sasakian manifold of type (α, β ...
Dae Ho Jin, Dimitris Fotakis
wiley   +1 more source