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Related papers: Non-K\"ahler complex structures on $R^4$

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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

This paper extends our earlier results to higher dimensions using a different approach, based on the rigidity of complex structures on certain domains.

Differential Geometry · Mathematics 2011-04-22 X-X. Chen , S. K. Donaldson

We construct a braided structure on the algebra of K\"ahler differential forms of a commutative algebra twisted by an endomorphism. This generalises the construction done in M. Karoubi, Quantum Methods in Algebraic Topology, see…

Algebraic Topology · Mathematics 2007-05-23 Max Karoubi , Mariano Suarez-Alvarez

We prove that compact quaternionic-K\"ahler manifolds of positive scalar curvature admit no almost complex structure, even in the weak sense, except for the complex Grassmannians $Gr_2(C^{n+2})$. We also prove that irreducible inner…

Differential Geometry · Mathematics 2011-04-26 Paul Gauduchon , Andrei Moroianu , Uwe Semmelmann

In this paper we consider structures of complex Poisson brackets on the space of smooth functions in a $n$-dimensional complex manifold generated by the $(1,1)$-form $d=\partial+\overline{\partial}$-closed and non-degenerate (with…

Differential Geometry · Mathematics 2023-07-25 Ibrahima Hamidine , ALi Mahamane Saminou

We investigate the following conjecture: all compact non-K\"ahler complex surfaces admit birational structures. After Inoue-Kobayashi-Ochiai, the remaining cases to study are essentially surfaces in class VII_0^+. In case of Kato surfaces…

Complex Variables · Mathematics 2016-01-13 Georges Dloussky

We discuss the integrability of orthogonal almost complex structures on Riemannian products of even-dimensional round spheres and give a partial answer to the question raised by E. Calabi concerning the existence of complex structures on a…

Differential Geometry · Mathematics 2013-01-31 Yunhee Euh , Kouei Sekigawa

A first classification of para-K\"{a}hler structures on four-dimensional Lie algebras was obtained by D. Calvaruzo in 2015. In this paper, we propose another classification based on the classification of symplectic Lie algebras. For each…

Differential Geometry · Mathematics 2020-08-14 N. K. Smolentsev , I. Y. Shagabudinova

In this paper we give new examples of QCH Kahler surfaces whose opposite almost Hermitian strucure is Hermitian and not locally conformally Kahler. In this way we give also a large class of examples of Hermitian surfaces with J-invariant…

Differential Geometry · Mathematics 2020-05-18 Wlodzimierz Jelonek

We introduce Hopf algebroid covariance on Woronowicz's differential calculus. Using it, we develop quite a general framework of noncommutative complex geometry that subsumes the one in [2]. We present transverse complex and K\"ahler…

Quantum Algebra · Mathematics 2021-05-11 Suvrajit Bhattacharjee , Indranil Biswas , Debashish Goswami

We show uniqueness up to sign of positive, orthogonal almost-Kaehler structures on any non-scalar flat Kaehler-Einstein surface.

Differential Geometry · Mathematics 2012-08-09 A. J. diScala , Paul-Andi Nagy

We construct new explicit toric scalar-flat K{\"a}hler ALE metrics on weighted projective spaces of non-compact type, which we use to obtain smooth extremal K{\"a}hler metrics on appropriate resolutions of orbifolds. In particular, we…

Differential Geometry · Mathematics 2016-03-25 Vestislav Apostolov , Yann Rollin

In this survey we discuss the problem of the existence of rational curves on complex surfaces, both in the K\"ahler and non-K\"ahler setup. We systematically go through the Enriques--Kodaira classification of complex surfaces to highlight…

Algebraic Geometry · Mathematics 2023-04-06 Giuseppe Barbaro , Filippo Fagioli , Ángel David Ríos Ortiz

The first example of a compact manifold admitting both complex and symplectic structures but not admitting a K\"ahler structure is the renowned Kodaira-Thurston manifold. We review its construction and show that this paradigm is very…

Symplectic Geometry · Mathematics 2014-05-01 Giovanni Bazzoni , Vicente Muñoz

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 construct the first examples of rationally convex surfaces in the complex plane with hyperbolic complex tangencies. In fact, we give two very different types of rationally convex surfaces: those that admit analytic fillings by…

Symplectic Geometry · Mathematics 2025-02-06 Georgios Dimitroglou Rizell , Mark G. Lawrence

We derive necessary conditions for a complex projective structure on a complex surface to arise via the Levi-Civita connection of a (pseudo-)K\"ahler metric. Furthermore we show that the (pseudo-)K\"ahler metrics defined on some domain in…

Differential Geometry · Mathematics 2023-07-19 Thomas Mettler

A new construction is presented of scalar-flat Kaehler metrics on non-minimal ruled surfaces. The method is based on the resolution of singularities of orbifold ruled surfaces which are closely related to rank-2 parabolically stable…

Differential Geometry · Mathematics 2007-05-23 Yann Rollin , Michael A. Singer

We study cohomological properties of complex manifolds. In particular, under suitable metric conditions, we extend to higher dimensions a result by A. Teleman, which provides an upper bound for the Bott-Chern cohomology in terms of Betti…

Differential Geometry · Mathematics 2019-12-23 Daniele Angella , Adriano Tomassini , Misha Verbitsky

We present new constructions of Kaehler metrics with constant scalar curvature on complex surfaces, in particular on certain del Pezzo surfaces. Some higher dimensional examples are provided as well.

Differential Geometry · Mathematics 2007-05-23 Yann Rollin , Michael A. Singer