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In this paper we study Kaehler manifolds that are strongly not relative to any projective Kaehler manifold, i.e. those Kaehler manifolds that do not share a Kaehler submanifold with any projective Kaehler manifold even when their metric is…

Differential Geometry · Mathematics 2016-11-08 Michela Zedda

We give a complete list, for $n \leq 6$, of non-isometric $\mathbb{T}^n$-invariant Kaehler-Einstein manifolds immersed in a finite dimensional complex projective space endowed with the Fubini-Study metric. This solves, in the aforementioned…

Differential Geometry · Mathematics 2026-02-18 Gianni Manno , Filippo Salis

We classify non-reductive four-dimensional homogeneous conformally Einstein manifolds.

Differential Geometry · Mathematics 2017-03-27 E. Calviño-Louzao , E. García-Río , I. Gutiérrez-Rodríguez , R. Vázquez-Lorenzo

Let (M,J) be a compact complex 2-manifold which which admits a Kaehler metric for which the integral of the scalar curvature is non-negative. Also suppose that M does not admit a Ricci-flat K\"ahler metric. Then if M is blown up at…

dg-ga · Mathematics 2008-02-03 Jongsu Kim , Claude LeBrun , Massimiliano Pontecorvo

It is shown that there are infinitely many compact orientable smooth 4-manifolds which do not admit Einstein metrics, but nevertheless satisfy the strict Hitchin-Thorpe inequality 2 chi > 3 |tau|. The examples in question arise as…

dg-ga · Mathematics 2008-02-03 Claude LeBrun

Two Kaehler metrics on one complex manifold are said to be c-projectively equivalent if their J-planar curves, i.e., curves defined by the property that their acceleration is complex proportional to their velocity, coincide. The degree of…

Differential Geometry · Mathematics 2015-10-02 Vladimir S. Matveev , Stefan Rosemann

In this paper we study smooth complex projective $4$-folds which are topologically equivalent. First we show that Fano fourfolds are never oriented homeomorphic to Ricci-flat projective fourfolds and that Calabi-Yau manifolds and…

Algebraic Geometry · Mathematics 2018-10-12 Keiji Oguiso , Thomas Peternell

We show that the blow-up of a generalized Kahler 4-manifold in a nondegenerate complex point admits a generalized Kahler metric. As with the blow-up of complex surfaces, this metric may be chosen to coincide with the original outside a…

Differential Geometry · Mathematics 2012-08-15 Gil R. Cavalcanti , Marco Gualtieri

We study generalized Kaehler manifolds for which the corresponding complex structures commute and classify completely the compact generalized Kaehler four-manifolds for which the induced complex structures yield opposite orientations.

Differential Geometry · Mathematics 2007-05-23 Vestislav Apostolov , Marco Gualtieri

Let $(M,\omega)$ be a compact K\"ahler manifold with negative holomorphic sectional curvature. It was proved by Wu-Yau and Tosatti-Yang that $M$ is necessarily projective and has ample canonical bundle. In this paper, we show that any…

Differential Geometry · Mathematics 2018-08-20 Henri Guenancia

We study Kahler surfaces with harmonic anti-selfdual Weyl tensor. We provide an explicit local description, which we use to obtain the complete classification in the compact case. We give new examples of extremal Kahler metrics, including…

Differential Geometry · Mathematics 2007-05-23 Vestislav Apostolov , David M. J. Calderbank , Paul Gauduchon

Using Hultgren's polytope formulation of the existence of coupled K\"ahler-Einstein (cKE) metrics on toric Fano manifolds, we construct explicit higher-dimensional toric Fano manifolds that admit two coupled K\"ahler-Einstein metrics but no…

Differential Geometry · Mathematics 2026-02-25 Naoto Yotsutani

We develop in detail the theory of c-projective geometry, a natural analogue of projective differential geometry adapted to complex manifolds. We realise it as a type of parabolic geometry and describe the associated Cartan or tractor…

Differential Geometry · Mathematics 2021-06-08 David M. J. Calderbank , Michael G. Eastwood , Vladimir S. Matveev , Katharina Neusser

We construct several examples of compactifications of Einstein metrics. We show that the Eguchi--Hanson instanton admits a projective compactification which is non--metric, and that a metric cone over any (pseudo)--Riemannian manifolds…

Differential Geometry · Mathematics 2020-02-12 Maciej Dunajski , A. Rod Gover , Alice Waterhouse

We study relations between quaternionic Riemannian manifolds admitting different types of symmetries. We show that any hyperKahler manifold admitting hyperKahler potential and triholomorphic action of S^1 can be constructed from another…

Differential Geometry · Mathematics 2009-11-13 Andriy Haydys

In a previous paper, the first two authors classified complete Ricci-flat ALF Riemannian 4-manifolds that are toric and Hermitian, but non-Kaehler. In this article, we consider general Ricci-flat deformations of such spaces, assuming only…

Differential Geometry · Mathematics 2023-11-14 Olivier Biquard , Paul Gauduchon , Claude LeBrun

We present a uniform framework generalising and extending the classical theories of projective differential geometry, c-projective geometry, and almost quaternionic geometry. Such geometries, which we call \emph{projective parabolic…

Differential Geometry · Mathematics 2016-05-17 George E. Frost

Motivated by a conjecture in [9] we prove that the K\"ahler cone over a regular complete Sasakian manifold is Ricci-flat and projectively induced if and only if it is flat. We also obtain that, up to $\mathcal D_a$-homothetic…

Differential Geometry · Mathematics 2024-06-18 Stefano Marini , Nicoletta Tardini , Michela Zedda

Four dimensional simply connected Lie groups admitting a pseudo K\"ahler metric are determined. The corresponding Lie algebras are modelized and the compatible pairs $(J,\omega)$ are parametrized up to complex isomorphism (where $J$ is a…

Differential Geometry · Mathematics 2007-05-23 Gabriela P. Ovando

The geometry of the target space of an N=(2,2) supersymmetry sigma-model carries a generalized Kahler structure. There always exists a real function, the generalized Kahler potential K, that encodes all the relevant local differential…

High Energy Physics - Theory · Physics 2009-11-13 Ulf Lindstrom , Martin Rocek , Rikard von Unge , Maxim Zabzine