On affine-maximal ruled surfaces.
On algebraic-geometrical parametrization of the constant mean curvature tori
On “All regular Landsberg metrics are always Berwald" by Z. I. Szabó.
On Almost Blaschke Manifolds I.
On almost cosymplectic (−1, μ, 0)-spaces
In our previous paper, almost cosymplectic (κ, μ, ν)-spaces were defined as the almost cosymplectic manifolds whose structure tensor fields satisfy a certain special curvature condition. Amongst other results, it was proved there that any almost cosymplectic (κ, μ, ν)-space can be -homothetically deformed to an almost cosymplectic −1, μ′, 0)-space. In the present paper, a complete local description of almost cosymplectic (−1, μ, 0)-speces is established: “models” of such spaces are constructed,...
On almost cosymplectic manifolds with the structure vector field belonging to the -nullity distribution.
On almost cosymplectic (κ,μ,ν)-spaces
An almost cosymplectic (κ,μ,ν)-space is by definition an almost cosymplectic manifold whose structure tensor fields φ, ξ, η, g satisfy a certain special curvature condition (see formula (eq1b)). This condition is invariant with respect to the so-called -homothetic transformations of almost cosymplectic structures. For such manifolds, the tensor fields φ, h (), A ( = -∇ξ) fulfill a certain system of differential equations. It is proved that the leaves of the canonical foliation of an almost cosymplectic...
On Almost Generalized Weakly Symmetric Kenmotsu Manifolds
This paper aims to introduce the notions of an almost generalized weakly symmetric Kenmotsu manifolds and an almost generalized weakly Ricci-symmetric Kenmotsu manifolds. The existence of an almost generalized weakly symmetric Kenmotsu manifold is ensured by a non-trivial example.
On almost geodesic mappings of the type of Riemannian spaces preserving a system -orthogonal hypersurfaces
On almost geodesic mappings between semisymmetric Riemannian spaces.
On almost geodesic mappings onto Riemannian spaces
On Almost Hyperbolic Spaces
On almost hyperbolic spaces.
On almost hyperHermitian structures on Riemannian manifolds and tangent bundles
Some results concerning almost hyperHermitian structures are considered, using the notions of the canonical connection and the second fundamental tensor field h of a structure on a Riemannian manifold which were introduced by the second author. With the help of any metric connection on an almost Hermitian manifold M an almost hyperHermitian structure can be constructed in the defined way on the tangent bundle TM. A similar construction was considered in [6], [7]. This structure includes two basic...
On almost Kähler type (2G₃) 4-manifolds
We study four-dimensional almost Kähler manifolds (M,g,J) which satisfy A. Gray's condition (G₃).
On almost product and almost decomposable manifolds.
On almost pseudo-conformally symmetric Ricci-recurrent manifolds with applications to relativity
The object of the present paper is to study almost pseudo-conformally symmetric Ricci-recurrent manifolds. The existence of almost pseudo-conformally symmetric Ricci-recurrent manifolds has been proved by an explicit example. Some geometric properties have been studied. Among others we prove that in such a manifold the vector field corresponding to the 1-form of recurrence is irrotational and the integral curves of the vector field are geodesic. We also study some global properties of such a...
On Almost Pseudo-Z-symmetric Manifolds
The object of the present paper is to study almost pseudo-Z-symmetric manifolds. Some geometric properties have been studied. Next we consider conformally flat almost pseudo-Z-symmetric manifolds. We obtain a sufficient condition for an almost pseudo-Z-symmetric manifold to be a quasi Einstein manifold. Also we prove that a totally umbilical hypersurface of a conformally flat () is a manifold of quasi constant curvature. Finally, we give an example to verify the result already obtained in Section...
On almost-Riemannian surfaces
An almost-Riemannian structure on a surface is a generalized Riemannian structure whose local orthonormal frames are given by Lie bracket generating pairs of vector fields that can become collinear. The distribution generated locally by orthonormal frames has maximal rank at almost every point of the surface, but in general it has rank 1 on a nonempty set which is generically a smooth curve. In this paper we provide a short introduction to 2-dimensional almost-Riemannian geometry highlighting its...
On alpha-Kenmotsu manifolds satisfying certain conditions.