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Kähler manifolds of quasi-constant holomorphic sectional curvatures

Georgi Ganchev, Vesselka Mihova (2008)

Open Mathematics

The Kähler manifolds of quasi-constant holomorphic sectional curvatures are introduced as Kähler manifolds with complex distribution of codimension two, whose holomorphic sectional curvature only depends on the corresponding point and the geometric angle, associated with the section. A curvature identity characterizing such manifolds is found. The biconformal group of transformations whose elements transform Kähler metrics into Kähler ones is introduced and biconformal tensor invariants are obtained....

Metric of special 2F-flat Riemannian spaces

Raad J. K. al Lami (2005)

Acta Universitatis Palackianae Olomucensis. Facultas Rerum Naturalium. Mathematica

In this paper we find the metric in an explicit shape of special 2 F -flat Riemannian spaces V n , i.e. spaces, which are 2 F -planar mapped on flat spaces. In this case it is supposed, that F is the cubic structure: F 3 = I .

Minimal submanifolds in 4 with a g.c.K. structure

Marian-Ioan Munteanu (2008)

Czechoslovak Mathematical Journal

In this paper we obtain all invariant, anti-invariant and C R submanifolds in ( 4 , g , J ) endowed with a globally conformal Kähler structure which are minimal and tangent or normal to the Lee vector field of the g.c.K. structure.

Novikov homology, jump loci and Massey products

Toshitake Kohno, Andrei Pajitnov (2014)

Open Mathematics

Let X be a finite CW complex, and ρ: π 1(X) → GL(l, ℂ) a representation. Any cohomology class α ∈ H 1(X, ℂ) gives rise to a deformation γ t of ρ defined by γ t (g) = ρ(g) exp(t〈α, g〉). We show that the cohomology of X with local coefficients γ gen corresponding to the generic point of the curve γ is computable from a spectral sequence starting from H*(X, ρ). We compute the differentials of the spectral sequence in terms of the Massey products and show that the spectral sequence degenerates in case...

On a Bianchi-type identity for the almost hermitian manifolds

Giovanni Battista Rizza (1988)

Atti della Accademia Nazionale dei Lincei. Classe di Scienze Fisiche, Matematiche e Naturali. Rendiconti Lincei. Matematica e Applicazioni

Almost hermitian manifolds, whose Riemann curvature tensor satisfies an almost complex Bianchi-type identity, are considered. Some local and global theorems are proved. The special cases of parakähler manifolds and of Kähler manifolds are examined.

On a generalized class of recurrent manifolds

Absos Ali Shaikh, Ananta Patra (2010)

Archivum Mathematicum

The object of the present paper is to introduce a non-flat Riemannian manifold called hyper-generalized recurrent manifolds and study its various geometric properties along with the existence of a proper example.

On almost cosymplectic (κ,μ,ν)-spaces

Piotr Dacko, Zbigniew Olszak (2005)

Banach Center Publications

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 ( = ( 1 / 2 ) ξ φ ), A ( = -∇ξ) fulfill a certain system of differential equations. It is proved that the leaves of the canonical foliation of an almost cosymplectic...

On Deszcz symmetries of Wintgen ideal submanifolds

Miroslava Petrović-Torgašev, Leopold C. A. Verstraelen (2008)

Archivum Mathematicum

It was conjectured in [26] that, for all submanifolds M n of all real space forms M ˜ n + m ( c ) , the Wintgen inequality ρ H 2 - ρ + c is valid at all points of M , whereby ρ is the normalised scalar curvature of the Riemannian manifold M and H 2 , respectively ρ , are the squared mean curvature and the normalised scalar normal curvature of the submanifold M in the ambient space M ˜ , and this conjecture was shown there to be true whenever codimension m = 2 . For a given Riemannian manifold M , this inequality can be interpreted as follows:...

On equitorsion holomorphically projective mappings of generalized Kählerian spaces

Mića S. Stanković, Svetislav M. Minčić, Ljubica S. Velimirović (2004)

Czechoslovak Mathematical Journal

In this paper we investigate holomorphically projective mappings of generalized Kählerian spaces. In the case of equitorsion holomorphically projective mappings of generalized Kählerian spaces we obtain five invariant geometric objects for these mappings.

On F 2 ε -planar mappings of (pseudo-) Riemannian manifolds

Irena Hinterleitner, Josef Mikeš, Patrik Peška (2014)

Archivum Mathematicum

We study special F -planar mappings between two n -dimensional (pseudo-) Riemannian manifolds. In 2003 Topalov introduced P Q ε -projectivity of Riemannian metrics, ε 1 , 1 + n . Later these mappings were studied by Matveev and Rosemann. They found that for ε = 0 they are projective. We show that P Q ε -projective equivalence corresponds to a special case of F -planar mapping studied by Mikeš and Sinyukov (1983) and F 2 -planar mappings (Mikeš, 1994), with F = Q . Moreover, the tensor P is derived from the tensor Q and the non-zero...

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