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We discovered that only a weakened version of the main lemma is true. We state the right version, and the remaining open problem: Is it possible to approximate holomorphic vector fields (or more generally, sections in a line bundle) on an…

Mathematical Physics · Physics 2007-05-23 Friedrich Wagemann

If $f$ is an automorphism of a compact simply connected K\"ahler manifold with trivial canonical bundle that fixes a K\"ahler class, then the order of $f$ is finite. We apply this well known result to construct compact non-K\"ahler…

Algebraic Geometry · Mathematics 2012-11-30 Gunnar Þór Magnússon

We prove that the surface gravity of a compact non-degenerate Cauchy horizon in a smooth vacuum spacetime, can be normalized to a non-zero constant. This result, combined with a recent result by Oliver Petersen and Istv\'an R\'acz, end up…

General Relativity and Quantum Cosmology · Physics 2020-06-17 Martín Reiris , Ignacio Bustamante

Killing vector fields of a closed homogeneous and isotropic universe are studied. It is shown that in general case there is no time-like Killing vector fields in such a universe. Two exceptional cases are revealed.

Differential Geometry · Mathematics 2007-08-21 Ruslan Sharipov

This paper presents a complete classification of left-invariant affine and projective vector fields on five-dimensional simply connected nilpotent Lie groups endowed with Riemannian metrics. Building on the classification of left-invariant…

Differential Geometry · Mathematics 2025-09-18 M. L. Foka , R. P. Nimpa , M. B. N. Djiadeu

We determine several necessary and sufficient conditions for a closed almost-complex orbifold $Q$ with cyclic local groups to admit a nonvanishing vector field. These conditions are stated separately in terms of the orbifold Euler-Satake…

Differential Geometry · Mathematics 2007-05-23 Christopher Seaton

We study the isometry groups and Killing vector fields of a family of pseudo-Riemannian metrics on Euclidean space which have neutral signature (3+2p,3+2p). All are p+2 curvature homogeneous, all have vanishing Weyl scalar invariants, all…

Differential Geometry · Mathematics 2007-05-23 P. Gilkey , S. Nikcevic

We demonstrate that the moduli space of Hermitian-Einstein connections $\text{M}^*_{HE}(M^{2n})$ of vector bundles over compact non-Gauduchon Hermitian manifolds $(M^{2n}, g, \omega)$ that exhibit a dilaton field $\Phi$ admit a strong…

Differential Geometry · Mathematics 2026-02-10 Georgios Papadopoulos

We study conformal Killing forms on compact 6-dimensional nearly K\"ahler manifolds. Our main result concerns forms of degree 3. Here we give a classification showing that all conformal Killing 3-forms are linear combinations of $d \omega$…

Differential Geometry · Mathematics 2019-03-19 Antonio M. Naveira , Uwe Semmelmann

We show that a unipotent vector bundle on a non-Kaehler compact complex manifold does not admit a flat holomorphic connection in general. We also construct examples of topologically trivial stable vector bundle on compact Gauduchon manifold…

Differential Geometry · Mathematics 2023-09-11 Indranil Biswas , Carlos Florentino

Killing forms on Riemannian manifolds are differential forms whose covariant derivative is totally skew--symmetric. We show that a compact simply connected symmetric space carries a non--parallel Killing $p$--form ($p\ge2$) if and only if…

Differential Geometry · Mathematics 2019-01-08 Florin Belgun , Andrei Moroianu , Uwe Semmelmann

In this paper, we establish a "pseudo-effective" version of the holonomy principle for compact K\"{a}hler manifolds with nonnegative holomorphic sectional curvature. As applications, we prove that if a compact complex manifold $M$ admits a…

Differential Geometry · Mathematics 2024-08-07 Shiyu Zhang , Xi Zhang

We give an equivalent definition of compact locally conformally hyperk\"ahler manifolds in terms of the existence of a nondegenerate complex two-form with natural properties. This is a conformal analogue of Beauville's theorem stating that…

Differential Geometry · Mathematics 2020-07-30 Liviu Ornea , Alexandra Otiman

In this paper, we show that any compact K$\"a$hler manifold homotopic to a compact Riemannian manifold with negative sectional curvature admits a K$\"a$hler-Einstein metric of general type. Moreover, we prove that, on a compact symplectic…

Differential Geometry · Mathematics 2017-11-10 Bing-Long Chen , Xiaokui Yang

We describe the compact Lorentzian $3$-manifolds admitting a parallel lightlike vector field. The classification of compact Lorentzian $3$-manifolds admitting non-isometric affine diffeomorphisms follows, together with the complete…

Differential Geometry · Mathematics 2015-06-26 Charles Boubel , Pierre Mounoud

We prove that there exist solutions for a non-parametric capillary problem in a wide class of Riemannian manifolds endowed with a Killing vector field. In other terms, we prove the existence of Killing graphs with prescribed mean curvature…

Differential Geometry · Mathematics 2016-01-20 Jorge H. S. Lira , Gabriela A. Wanderley

We prove that when Hodge theory survives on non-compact symplectic manifolds, a compact symplectic Lie group action having fixed points is necessarily Hamiltonian, provided the associated almost complex structure preserves the space of…

Symplectic Geometry · Mathematics 2015-03-17 Alvaro Pelayo , Tudor S. Ratiu

I extend the framework of rigid analytic geometry to the setting of algebraic geometry relative to monoids, and study the associated notions of separated, proper, and overconvergent morphisms. The category of affine manifolds embeds as a…

Algebraic Geometry · Mathematics 2015-05-29 Andrew W. Macpherson

Let (M, g) be a compact Einstein manifold with non-empty boundary. We prove that Killing fields at the boundary extend to Killing fields of any (M, g) provided the boundary is weakly convex and a simple condition on the fundamental group…

Differential Geometry · Mathematics 2017-02-21 Michael T Anderson

Let $X$ be a normal, connected and projective variety over an algebraically closed field $k$. It is known that a vector bundle $V$ on $X$ is essentially finite if and only if it is trivialized by a proper surjective morphism $f:Y\to X$. In…

Algebraic Geometry · Mathematics 2017-02-14 Fabio Tonini , Lei Zhang
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