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Let (J,g) be a Hermitian structure on a compact nilmanifold M with invariant complex structure J and compatible metric g, which is not required to be invariant. We give classifications of 6-dimensional nilmanifolds M admitting strong…

Differential Geometry · Mathematics 2007-05-23 Luis Ugarte

We give a partial account of some problems concerning cohomological invariants and metric properties of complex non-K\"ahler manifolds.

Differential Geometry · Mathematics 2026-02-04 Daniele Angella , Nicoletta Tardini

In this paper we introduce radical transversal lightlike hypersurfaces of almost complex manifolds with Norden metric. The study of these hypersurfaces is motivated by the fact that for indefinite almost Hermitian manifolds this class of…

Differential Geometry · Mathematics 2013-02-18 Galia Nakova

In this paper, we consider a non-degenerate CR manifold (M,H(M),J) with a given pseudo-Hermitian 1-form {\theta}, and endow the CR distribution H(M) with any Hermitian metric h instead of the Levi form L_{{\theta}}. This induces a natural…

Differential Geometry · Mathematics 2024-08-21 Yuxin Dong , Yibin Ren

This article studies left-invariant Hermitian structures on Lie groups with two-dimensional commutator subgroups. We provide an explicit classification for two specific types of such structures, which we designate as Type I and Type II.…

Differential Geometry · Mathematics 2026-02-17 Hamid Reza Salimi Moghaddam

We prove several K\"ahlerness criteria for compact Hermitian surfaces under semi-definiteness assumptions on natural Ricci curvatures of the Strominger-Bismut connection. The key tools for proving these results are explicit identities…

Differential Geometry · Mathematics 2026-05-27 Liangdi Zhang

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 proved the existence of supersymmetric Hermitian metrics with torsion on a class of non-Kaehler manifolds.

High Energy Physics - Theory · Physics 2007-05-23 Ji-Xiang Fu , Shing-Tung Yau

In this paper, we prove that any K\"ahler Ricci shrinker surface has bounded sectional curvature. Combining this estimate with earlier work by many authors, we provide a complete classification of all K\"ahler Ricci shrinker surfaces.

Differential Geometry · Mathematics 2025-02-18 Yu Li , Bing Wang

We classify quadratic spaces over endomorphism fields of K3 surfaces. We consider both totally real and CM cases.

Algebraic Geometry · Mathematics 2012-10-02 Evgeny Mayanskiy

Gray & Hervella gave a classification of almost Hermitian structures (g,I) into 16 classes. We systematically study the interaction between these classes when one has an almost hyper-Hermitian structure (g,I,J,K). In general dimension we…

Differential Geometry · Mathematics 2007-05-23 Francisco Martin Cabrera , Andrew Swann

Polyhedral K\"ahler surfaces are a class of complex surfaces, which are flat everywhere except on a two-dimensional skeleton. They are defined as a generalisation of the "gluing a polygon side by side" construction of flat Riemann surfaces.…

Algebraic Geometry · Mathematics 2018-06-11 Cécile Gachet

We give a mostly self-contained proof of the classification of non-Kahler surfaces based on Buchdahl-Lamari theorem. We also prove that all non-Kahler surfaces which are not of class VII are locally conformally Kahler.

Algebraic Geometry · Mathematics 2021-08-12 Liviu Ornea , Victor Vuletescu , Misha Verbitsky

We construct the first examples of non-K\"ahler complex structures on $R^4$. These complex surfaces have some analogies with the complex structures constructed in early Fifties by Calabi and Eckmann on the products of two odd-dimensional…

Geometric Topology · Mathematics 2017-06-14 Antonio J. Di Scala , Naohiko Kasuya , Daniele Zuddas

Motivated by a recent work of Chen-Zheng [8] on Strominger space forms, we prove that a compact Hermitian surface with pointwise constant holomorphic sectional curvature with respect to a Gauduchon connection $\nabla^t $ is either K\"ahler,…

Differential Geometry · Mathematics 2022-02-15 Haojie Chen , Xiaolan Nie

We investigate the asymptotic geometry of Hermitian non-K\"ahler Ricci-flat metrics with finite $\int|Rm|^2$ at infinity. Specifically, we prove: 1. Any such metric is asymptotic to an ALE, ALF-A, AF, skewed special Kasner, ALH* model at…

Differential Geometry · Mathematics 2024-10-17 Mingyang Li

In dimension greater than four, we prove that if a Hermitian non-Kaehler manifold is of pointwise constant antiholomorphic sectional curvatures, then it is of constant sectional curvatures.

Differential Geometry · Mathematics 2007-07-23 Georgi Ganchev , Ognian Kassabov

We show that supertwistor spaces constructed as a Kahler quotient of a hyperkahler cone (HKC) with equal numbers of bosonic and fermionic coordinates are Ricci-flat, and hence, Calabi-Yau. We study deformations of the supertwistor space…

High Energy Physics - Theory · Physics 2009-11-11 Ulf Lindstrom , Martin Rocek , Rikard von Unge

A Hermitian metric on a complex manifold is called SKT (strong K\"ahler with torsion) if the Bismut torsion $3$-form $H$ is closed. As the conformal generalization of the SKT condition, we introduce a new type of Hermitian structure, called…

Differential Geometry · Mathematics 2022-11-09 Bachir Djebbar , Ana Cristina Ferreira , Anna Fino , Nourhane Zineb Larbi Youcef

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