A characterization for isometries and conformal mappings of pseudo-Riemannian manifolds.
A class of metrics on tangent bundles of pseudo-Riemannian manifolds
We provide the tangent bundle of pseudo-Riemannian manifold with the Sasaki metric and the neutral metric . First we show that the holonomy group of contains the one of . What allows us to show that if is indecomposable reducible, then the basis manifold is also indecomposable-reducible. We determine completely the holonomy group of according to the one of . Secondly we found conditions on the base manifold under which ( respectively ) is Kählerian, locally symmetric or Einstein...
A generalization of Frenet's frame for non-degenerate quadratic forms with any index
A new characterization of -stable hypersurfaces in space forms
In this paper we study the -stability of closed hypersurfaces with constant -th mean curvature in Riemannian manifolds of constant sectional curvature. In this setting, we obtain a characterization of the -stable ones through of the analysis of the first eigenvalue of an operator naturally attached to the -th mean curvature.
A particular conformally symmetric space
A property on geodesic mappings of pseudo-symmetric Riemannian manifolds.
A study on the one parameter Lorentzian spherical motions.
About twistor spinors with zero in Lorentzian geometry.
Affine surfaces with planar affine normals in 3-dimensional Minkowski space .
Algebraic restrictions on geometric realizations of curvature models
We generalize a previous result concerning the geometric realizability of model spaces as curvature homogeneous spaces, and investigate applications of this approach. We find algebraic restrictions to realize a model space as a curvature homogeneous space up to any order, and study the implications of geometrically realizing a model space as a locally symmetric space. We also present algebraic restrictions to realize a curvature model as a homothety curvature homogeneous space up to even orders,...
An alternative moving frame for tubular surfaces around time-like curves in the Minkowski 3-space.
An example of an almost hyperbolic Hermitian manifold.
An Osserman-type condition on g.f.f-manifolds with Lorentz metric
A condition of Osserman type, called the φ-null Osserman condition, is introduced and studied in the context of Lorentz globally framed f-manifolds. An explicit example shows the naturality of this condition in the setting of Lorentz 𝓢-manifolds. We prove that a Lorentz 𝓢-manifold with constant φ-sectional curvature is φ-null Osserman, extending a well-known result in the case of Lorentz Sasaki space forms. Then we state a characterization of a particular class of φ-null Osserman 𝓢-manifolds....
Area-stationary surfaces in neutral Kähler 4-manifolds.