Some Notes on the Radon Transform and Integral Geometry.
Some Para-Hermitian Related Complex Structures and Non-existence of Semi-Riemannian Metric on Some Spheres
It is shown that the spheres S^(2n) (resp: S^k with k ≡ 1 mod 4) can be given neither an indefinite metric of any signature (resp: of signature (r, k − r) with 2 ≤ r ≤ k − 2) nor an almost paracomplex structure. Further for every given Riemannian metric on an almost para-Hermitian manifold with the associated 2-form φ one can construct an almost Hermitian structure (under certain conditions, two different almost Hermitian structures) whose associated 2-form(s) is φ.
Some perturbation results for non-linear problems
We discuss the existence of closed geodesic on a Riemannian manifold and the existence of periodic solution of second order Hamiltonian systems.
Some problems of differential geometry of one class of spaces of supporting elements
Some problems of global analysis on asymptotically simple manifolds
Some progress in conformal geometry.
Some properties of a closed concircular almost contact manifold.
Some properties of almost -paracontact manifolds.
Some properties of Carnot-Carathéodory balls in the Heisenberg group
Using the exact representation of Carnot-Carathéodory balls in the Heisenberg group, we prove that: 1. in the classical sense for all with , where is the distance from the origin; 2. Metric balls are not optimal isoperimetric sets in the Heisenberg group.
Some properties of distinguished vector fields on Riemannian.
Some properties of fundamental bipoint tensor
Some properties of geodesic semi E-b-vex functions
In this study, we introduce a new class of function called geodesic semi E-b-vex functions and generalized geodesic semi E-b-vex functions and discuss some of their properties.
Some properties of Jordan-Ehlers spacetime.
Some Properties of Lorentzian -Sasakian Manifolds with Respect to Quarter-symmetric Metric Connection
The aim of this paper is to study generalized recurrent, generalized Ricci-recurrent, weakly symmetric and weakly Ricci-symmetric, semi-generalized recurrent, semi-generalized Ricci-recurrent Lorentzian -Sasakian manifold with respect to quarter-symmetric metric connection. Finally, we give an example of 3-dimensional Lorentzian -Sasakian manifold with respect to quarter-symmetric metric connection.
Some properties of para-Kähler-Walker metrics
A Walker 4-manifold is a pseudo-Riemannian manifold (M₄,g) of neutral signature, which admits a field of parallel null 2-planes. We study almost paracomplex structures on 4-dimensional para-Kähler-Walker manifolds. In particular, we obtain conditions under which these almost paracomplex structures are integrable, and the corresponding para-Kähler forms are symplectic. We also show that Petean's example of a nonflat indefinite Kähler-Einstein 4-manifold is a special case of our constructions.
Some properties of semibase Pfaffian forms on the tangent bundle
Some properties of tangent Dirac structures of higher order
Let be a smooth manifold. The tangent lift of Dirac structure on was originally studied by T. Courant in [3]. The tangent lift of higher order of Dirac structure on has been studied in [10], where tangent Dirac structure of higher order are described locally. In this paper we give an intrinsic construction of tangent Dirac structure of higher order denoted by and we study some properties of this Dirac structure. In particular, we study the Lie algebroid and the presymplectic foliation...
Some Properties of the Curvature Operator of a Riemannian Manifold.
Some Properties of the Fundamental Group of a Fuchsian Manifold.
Some properties of the locally conformal Kähler manifold