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Formality and the Lefschetz property in symplectic and cosymplectic geometry

Giovanni Bazzoni, Marisa Fernández, Vicente Muñoz (2015)

Complex Manifolds

We review topological properties of Kähler and symplectic manifolds, and of their odd-dimensional counterparts, coKähler and cosymplectic manifolds. We focus on formality, Lefschetz property and parity of Betti numbers, also distinguishing the simply-connected case (in the Kähler/symplectic situation) and the b1 = 1 case (in the coKähler/cosymplectic situation).

Free CR distributions

Gerd Schmalz, Jan Slovák (2012)

Open Mathematics

There are only some exceptional CR dimensions and codimensions such that the geometries enjoy a discrete classification of the pointwise types of the homogeneous models. The cases of CR dimensions n and codimensions n 2 are among the very few possibilities of the so-called parabolic geometries. Indeed, the homogeneous model turns out to be PSU(n+1,n)/P with a suitable parabolic subgroup P. We study the geometric properties of such real (2n+n 2)-dimensional submanifolds in ℂ n + n 2 for all n > 1. In...

g -natural metrics of constant curvature on unit tangent sphere bundles

M. T. K. Abbassi, Giovanni Calvaruso (2012)

Archivum Mathematicum

We completely classify Riemannian g -natural metrics of constant sectional curvature on the unit tangent sphere bundle T 1 M of a Riemannian manifold ( M , g ) . Since the base manifold M turns out to be necessarily two-dimensional, weaker curvature conditions are also investigated for a Riemannian g -natural metric on the unit tangent sphere bundle of a Riemannian surface.

G1-structures of second order.

Demetra Demetropoulou Psomopoulou (1992)

Publicacions Matemàtiques

We introduce a generalization to the second order of the notion of the G1-structure, the so called generalized almost tangent structure. For this purpose, the concepts of the second order frame bundle H2(Vm), its structural group Lm2 and its associated tangent bundle of second order T2(Vm) of a differentiable manifold Vm are described from the point of view that is used. Then, a G1-structure of second order -called G12-structure- is constructed on Vm by an endorphism J acting on T2(Vm), satisfying...

Generalized Kählerian manifolds and transformation of generalized contact structures

Habib Bouzir, Gherici Beldjilali, Mohamed Belkhelfa, Aissa Wade (2017)

Archivum Mathematicum

The aim of this paper is two-fold. First, new generalized Kähler manifolds are constructed starting from both classical almost contact metric and almost Kählerian manifolds. Second, the transformation construction on classical Riemannian manifolds is extended to the generalized geometry setting.

Generalized m-quasi-Einstein metric within the framework of Sasakian and K-contact manifolds

Amalendu Ghosh (2015)

Annales Polonici Mathematici

We consider generalized m-quasi-Einstein metric within the framework of Sasakian and K-contact manifolds. First, we prove that a complete Sasakian manifold M admitting a generalized m-quasi-Einstein metric is compact and isometric to the unit sphere S 2 n + 1 . Next, we generalize this to complete K-contact manifolds with m ≠ 1.

Generalized Tanaka-Webster and Levi-Civita connections for normal Jacobi operator in complex two-plane Grassmannians

Eunmi Pak, Juan de Dios Pérez, Young Jin Suh (2015)

Czechoslovak Mathematical Journal

We study classifying problems of real hypersurfaces in a complex two-plane Grassmannian G 2 ( ℂ m + 2 ) . In relation to the generalized Tanaka-Webster connection, we consider that the generalized Tanaka-Webster derivative of the normal Jacobi operator coincides with the covariant derivative. In this case, we prove complete classifications for real hypersurfaces in G 2 ( ℂ m + 2 ) satisfying such conditions.

Generic one-step bracket-generating distributions of rank four

Chiara De Zanet (2015)

Archivum Mathematicum

We give a uniform, explicit description of the generic types of one–step bracket–generating distributions of rank four. A manifold carrying such a structure has dimension at least five and no higher than ten. For each of the generic types, we give a brief description of the resulting class of generic distributions and of geometries equivalent to them. For dimensions different from eight and nine, these are available in the literature. The remaining two cases are dealt with in my doctoral thesis.

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