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We study almost K\"ahler manifolds whose curvature tensor satisfies the second curvature condition of Gray (shortly ${\cal{AK}}_2$). This condition is interpreted in terms of the first canonical Hermitian connection. It turns out that this…

Differential Geometry · Mathematics 2007-05-23 Paul-Andi Nagy

We study special almost Kaehler manifolds whose curvature tensor satisfies the second curvature condition of Gray. It is shown that for such manifolds, the torsion of the first canonical Hermitian is parallel. This enables us to show that…

Differential Geometry · Mathematics 2007-05-23 Paul-Andi Nagy

We characterize quasi K\"ahler manifolds whose curvature tensor associated to the canonical Hermitian connection satisfies the first Bianchi identity. This condition is related with the third Gray identity and in the almost K\"ahler case…

Differential Geometry · Mathematics 2011-01-11 Antonio J. Di Scala , Luigi Vezzoni

We consider complete nearly K\"ahler manifolds with the canonical Hermitian connection. We prove some metric properties of strict nearly K\"ahler manifolds and give a sufficient condition for the reducibility of the canonical Hermitian…

Differential Geometry · Mathematics 2007-05-23 Paul-Andi Nagy

The subject of investigations are the almost hypercomplex manifolds with Hermitian and anti-Hermitian (Norden) metrics. A linear connection D is introduced such that the structure of these manifolds is parallel with respect to D and its…

Differential Geometry · Mathematics 2012-05-08 Mancho Manev , Kostadin Gribachev

We consider an almost complex manifold with Norden metric (i. e. a metric with respect to which the almost complex structure is an anti-isometry). On such a manifold we study a linear connection preserving the almost complex structure and…

Differential Geometry · Mathematics 2011-01-24 Dimitar Mekerov

The structure of nearly K\"ahler manifolds was studied by Gray in several papers. More recently, a relevant progress on the subject has been done by Nagy. Among other results, he proved that a strict and complete nearly K\"ahler manifold is…

Differential Geometry · Mathematics 2010-11-29 J. C. González Dávila , F. Martín Cabrera

A Theorem of Kirichenko states that the torsion 3-form of the characteristic connection of a nearly K\"ahler manifold is parallel. On the other side, any almost hermitian manifold of type $\mathrm{G}_1$ admits a unique connection with…

Differential Geometry · Mathematics 2009-11-10 Bogdan Alexandrov , Thomas Friedrich , Nils Schoemann

We show that a Hermitian algebraic curvature model satisfies the Gray identity if and only if it is geometrically realizable by a Hermitian manifold. Furthermore, such a curvature model can in fact be realized by a Hermitian manifold of…

Differential Geometry · Mathematics 2008-12-16 M. Brozos-Vazquez , P. Gilkey , H. Kang , S. Nikcevic

We study curvature properties of four-dimensional almost Hermitian manifolds with vanishing Bochner curvature tensor as defined by Tricerri and Vanhecke. We give local structure theorems for such Kaehler manifolds, and find out several…

Differential Geometry · Mathematics 2007-10-11 Y. Euh , J. Lee , J. H. Park , K. Sekigawa , A. Yamada

The covariant derivative of the K\"ahler form of an almost pseudo-Hermitian or of an almost para-Hermitian manifold satisfies certain algebraic relations. We show, conversely, that any 3-tensor which satisfies these algebraic relations can…

Differential Geometry · Mathematics 2010-12-23 Miguel Brozos-Vázquez , Eduardo García-Río , Peter Gilkey , Luis Hervella

The $B$-connection on almost complex manifolds with Norden metric is an analogue of the first canonical connection of Lihnerovich in Hermitian geometry. In the present paper it is considered a $B$-connection in the class of the…

Differential Geometry · Mathematics 2009-07-14 Dimitar Mekerov

We obtain a classification theorem for non Kaehler nearly Kaehler manifolds with vanishing Bochner curvature tensor (introduced by Tricerri and Vanhecke).

Differential Geometry · Mathematics 2009-10-08 Ognian Kassabov

The study of quasi-K\"ahler Chern-flat almost Hermitian manifolds is strictly related to the study of anti-bi-invariant almost complex Lie algebras. In the present paper we show that quasi-K\"ahler Chern-flat almost Hermitian structures on…

Differential Geometry · Mathematics 2011-01-11 Antonio J. Di Scala , Jorge Lauret , Luigi Vezzoni

We classify, up to a local isometry, all non-Kahler almost Kahler 4-manifolds for which the fundamental 2-form is an eigenform of the Weyl tensor, and whose Ricci tensor is invariant with respect to the almost complex structure.…

Differential Geometry · Mathematics 2007-05-23 Vestislav Apostolov , John Armstrong , Tedi Draghici

Almost hypercomplex manifolds with Hermitian and anti-Hermitian metrics are considered. A linear connection $D$ is introduced such that the structure of these manifolds is parallel with respect to D. Of special interest is the class of the…

Differential Geometry · Mathematics 2012-05-08 Mancho Manev

We consider strict and complete nearly Kaehler manifolds with the canonical Hermitian connection. The holonomy representation of the canonical Hermitian connection is studied. We show that a strict and complete nearly Kaehler is locally a…

Differential Geometry · Mathematics 2007-05-23 Paul-Andi Nagy

The characteristic connection of an almost hermitian structure is a hermitian connection with totally skew-symmetric torsion. The case of parallel torsion in dimension six is of particular interest. In this work, we give a full…

Differential Geometry · Mathematics 2009-11-13 Nils Schoemann

For complete complex connections on almost complex manifolds we introduce a natural definition of compactification. This is based on almost c--projective geometry, which is the almost complex analogue of projective differential geometry.…

Differential Geometry · Mathematics 2019-10-31 Andreas Cap , A. Rod Gover

We show that the conservation of energy-momentum tensor of a gravitational model with Einstein-Hilbert like action on a nearly Kahler manifold with the scalar curvature of a curvature-like tensor, is consistent with the nearly Kahler…

High Energy Physics - Theory · Physics 2015-02-10 F. Naderi , A. Rezaei-Aghdam , F. Darabi
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