Results 31 to 40 of about 207 (126)
Totally Umbilical Lightlike Hypersurfaces in Robertson-Walker Spacetimes [PDF]
ISRN Geometry, 2014 We study the problem of lightlike hypersurface immersed into Robertson-Walker (RW) spacetimes in this paper, where the screen bundle of the hypersurface has constant higher order mean curvature. We consider the following question: under what conditions is the compact lightlike hypersurface totally umbilical?
Dong, Junhong, Liu, Ximin
openaire +1 more source
On a property of W4 -manifolds
Дифференциальная геометрия многообразий фигур, 2020 The properties of almost Hermitian manifolds belonging to the Gray — Hervella class W4 are considered. The almost Hermitian manifolds of this class were studied by such outstanding geometers like Alfred Gray, Izu Vaisman, and Vadim Feodorovich Kirichenko.
M.B. Banaru
doaj +1 more source
Hiroshima Mathematical Journal, 1990 Let M be a complete hypersurface with constant mean curvature of a space form of index s \((=0\) or 1). A sufficient condition, which is established between the length of the second fundamental form and the mean curvature, is given for M to be totally umbilical. This result generalizes the reviewer's result [Proc. Am. Math. Soc.
Cheng, Qing Ming, Nakagawa, Hisao
openaire +2 more sources
Hypersurfaces of a Sasakian manifold - revisited
Journal of Inequalities and Applications, 2021 We study orientable hypersurfaces in a Sasakian manifold. The structure vector field ξ of a Sasakian manifold determines a vector field v on a hypersurface that is the component of the Reeb vector field ξ tangential to the hypersurface, and it also gives
Sharief Deshmukh +3 more
doaj +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. +2 more
core +1 more source
Quasi‐Einstein Hypersurfaces of Complex Space Forms
Advances in Mathematical Physics, Volume 2020, Issue 1, 2020., 2020 Based on a well‐known fact that there are no Einstein hypersurfaces in a nonflat complex space form, in this article, we study the quasi‐Einstein condition, which is a generalization of an Einstein metric, on the real hypersurface of a nonflat complex space form. For the real hypersurface with quasi‐Einstein metric of a complex Euclidean space, we also
Xuehui Cui, Guozhen Lu, Xiaomin Chen
wiley +1 more source
ON NON-INVARIANT HYPERSURFACES OF AN ε-PARA SASAKIAN MANIFOLD [PDF]
, 2020 In the present paper non-invariant hypersurfaces of an ε- para Sasakian manifold of an induced structure (f,g,u,v,λ) are studied. Some properties followed by this structure are obtained.
Kishor, Shyam, Kanaujia, Prerna
core +1 more source
Totally umbilical hypersurfaces of Spinc manifolds carrying special spinor fields [PDF]
International Journal of Mathematics, 2020 Under some dimension restrictions, we prove that totally umbilical hypersurfaces of Spin[Formula: see text] manifolds carrying a parallel, real or imaginary Killing spinor are of constant mean curvature. This extends to the Spin[Formula: see text] case the result of Kowalski stating that, every totally umbilical hypersurface of an Einstein manifold of
Große, Nadine, Nakad, Roger
openaire +4 more sources
Characterization of totally umbilic hypersurfaces in a space form by circles [PDF]
Czechoslovak Mathematical Journal, 2005 In this paper we characterize totally umbilic hypersurfaces in a space form by a property of the extrinsic shape of circles on hypersurfaces. This characterization corresponds to characterizations of isoparametric hypersurfaces in a space form by properties of the extrinsic shape of geodesics due to Kimura-Maeda.
Toshiaki Adachi, Sadahiro Maeda
openaire +1 more source
Totally umbilic null hypersurfaces in generalized Robertson–Walker spaces
Differential Geometry and its Applications, 2015 We show that there is a correspondence between totally umbilic null hypersurfaces in generalized Robertson-Walker spaces and twisted decompositions of the fibre. This allows us to prove that nullcones are the unique totally umbilic null hypersurfaces in the closed Friedmann Cosmological model.
Manuel Gutiérrez, Benjamín Olea
openaire +6 more sources