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We discuss our recent results on the existence and classification problem of complex and Kaehler structures on compact solvmanifolds. In particular, we determine in this paper all the complex surfaces which are diffeomorphic to compact…

Complex Variables · Mathematics 2008-04-30 Keizo Hasegawa

We give a characterization of almost abelian Lie groups carrying left invariant hypercomplex structures and we show that the corresponding Obata connection is always flat. We determine when such Lie groups admit HKT metrics and study the…

Differential Geometry · Mathematics 2023-04-26 Adrián Andrada , María Laura Barberis

A locally conformally Kaehler (l.c.K.) manifold is a complex manifold admitting a Kaehler covering $\tilde M$, with each deck transformation acting by Kaehler homotheties. A compact l.c.K. manifold is Vaisman if it admits a holomorphic flow…

Differential Geometry · Mathematics 2019-09-02 Liviu Ornea , Misha Verbitsky

We study holomorphic geometric structures on non-K\"ahler compact complex manifolds with trivial canonical line bundle. For Vaisman Calabi-Yau manifolds we prove that all holomorphic geometric structures of affine type on them are locally…

Differential Geometry · Mathematics 2026-05-22 Indranil Biswas , Sorin Dumitrescu

For a compact complex manifold, we introduce holomorphic foliations associated with certain abelian subgroups of the automorphism group. Such foliations are generalizations of holomorphic principal torus bundles. If there exists a…

Complex Variables · Mathematics 2018-01-22 Hiroaki Ishida , Hisashi Kasuya

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

For contact manifolds $(M, \eta)$ a complexification $M^c$ is constructed to which the contact form $\eta$ extends such that the exterior derivative of the extended form is K\"ahlerian. In the case of a proper action of an extendable Lie…

Complex Variables · Mathematics 2010-06-08 Ayse Kurtdere

We use the natural lifts of the fundamental tensor field g to the cotangent bundle T*M of a Riemannian manifold (M,g), in order to construct an almost Hermitian structure (G,J) of diagonal type on T*M. The obtained almost complex structure…

Differential Geometry · Mathematics 2007-05-23 Vasile Oproiu , Dumitru Daniel Porosniuc

We study a special type of almost complex structures, called pure and full and introduced by T.J. Li and W. Zhang, in relation to symplectic structures and Hard Lefschetz condition. We provide sufficient conditions to the existence of the…

Differential Geometry · Mathematics 2009-06-04 Anna Fino , Adriano Tomassini

We characterize compact locally conformally K\"ahler (l.c.K.) manifolds under the assumption of a purely conformal, holomorphic circle action. As an application, we determine the structure of the compact l.c.K. manifolds with parallel Lee…

Differential Geometry · Mathematics 2007-05-23 Yoshinobu Kamishima , Liviu Ornea

We give a construction of integrable complex structures on the total space of a smooth principal bundle over a complex manifold, with an even dimensional compact Lie group as structure group, under certain conditions. This generalizes the…

Complex Variables · Mathematics 2018-02-09 Mainak Poddar , Ajay Singh Thakur

The Kaehler manifolds of quasi-constant holomorphic sectional curvatures are introduced as Kaehler manifolds with complex distribution of codimension two, whose holomorphic sectional curvature only depends on the corresponding point and the…

Differential Geometry · Mathematics 2008-03-04 Georgi Ganchev , Vesselka Mihova

We extend the notion of a Sasakian structure from the classical setting of a cooriented contact manifold, where it is given by a compatibility between a contact form $\eta$ and a Riemannian metric $g_M$ on $M$, to the case of an arbitrary…

Differential Geometry · Mathematics 2026-05-27 Katarzyna Grabowska , Janusz Grabowski , Rouzbeh Mohseni

The main aim of this paper is to construct a complex analytic family of symmetric projective K3 surfaces through a compactifiable deformation family of complete quasi-projective varieties from $\operatorname{CP}^2…

Complex Variables · Mathematics 2025-07-29 Fan Xu

Almost contact structures can be identified with sections of a twistor bundle and this allows to define their harmonicity, as sections or maps. We consider the class of nearly cosymplectic almost contact structures on a Riemannian manifold…

Differential Geometry · Mathematics 2011-09-14 E. Loubeau , E. Vergara-Diaz

We prove various classification results for homogeneous locally conformally symplectic manifolds. In particular, we show that a homogeneous locally conformally Kaehler manifold of a reductive group is of Vaisman type, if the normalizer of…

Differential Geometry · Mathematics 2016-01-15 Dmitri V. Alekseevsky , Vicente Cortes , Keizo Hasegawa , Yoshinobu Kamishima

We provide families of compact $(n + 1)$-dimensional complex non K\"ahler manifolds satisfying the $\partial\bar{\partial}$-Lemma, with holomoprhically trivial canonical bundle, carrying a balanced metric and with no $p$-K\"ahler…

Differential Geometry · Mathematics 2024-03-18 Andrea Cattaneo , Adriano Tomassini

For a given complex n-fold M we present an explicit construction of all complex (n+1)-folds which are principal holomorphic T2-fibrations over M. For physical applications we consider the case of M being a Calabi-Yau 2-fold. We show that…

High Energy Physics - Theory · Physics 2009-11-07 Edward Goldstein , Sergey Prokushkin

In this thesis, we study cohomological properties of non-K\"ahler manifolds. In particular, we are concerned in investigating the cohomology of compact (almost-)complex manifolds, and of manifolds endowed with special structures, e.g.,…

Differential Geometry · Mathematics 2013-02-05 Daniele Angella

We show that if a connected compact k\"ahlerian surface $M$ with nonpositive gaussian curvature is furnished with a closed conformal vector field $\xi$ whose singular points are isolated, then $M$ is isometric to a flat torus and $\xi$ is…

Differential Geometry · Mathematics 2017-05-31 Antonio Caminha