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We classify those manifolds mentioned in the title which have finite topological type. Namely we show any such connected M is isomorphic to a hyperkaehler quotient of a flat quaternionic vector space by an abelian group. We also show that a…

Differential Geometry · Mathematics 2007-05-23 Roger Bielawski

We describe explicitly all quaternionic contact hypersurfaces (qc-hypersurfaces) in the flat quaternion space $\Hnn$ and the quaternion projective space. We show that up to a quaternionic affine transformation a qc-hypersurface in $\Hnn$ is…

Differential Geometry · Mathematics 2014-06-18 Stefan Ivanov , Ivan Minchev , Dimiter Vassilev

We consider strict and complete nearly Kaehler manifolds with the canonical Hermitian connection. The holonomy representation of the canonical Hermitian connection is studied. We show that a strict and complete nearly Kaehler is locally a…

Differential Geometry · Mathematics 2007-05-23 Paul-Andi Nagy

In Kaehler manifolds are investigated conformally flat totally real submanifolds, which are semiparallel or have semiparallel mean curvature vector.

Differential Geometry · Mathematics 2010-01-26 Ognian Kassabov

The purpose of the present paper is to study the differential geometric properties of a quaternion CR-submanifold in a locally conformal quaternion Kaehler manifold.

Differential Geometry · Mathematics 2007-08-10 Bayram Sahin

Notions of self-dual and anti self-dual almost quaternionic structures are introduced. The complete classification of self-dual and anti self-dual generalized Kaehler manifolds is obtained.

dg-ga · Mathematics 2008-02-03 V. F. Kirichenko , O. E Arseneva

Maximally symmetric manifolds with holonomy in the unitary quaternionic group Sp(d/4) emerge from the non-Abelian Kaluza-Klein reduction of conformally flat spaces. Thus, all special manifolds with constant properly `holonomy-related'…

Mathematical Physics · Physics 2015-05-20 Paolo Maraner , Jiannis K. Pachos

We provide a general criteria for the integrability of the almost para-quaternionic structure of an almost para-quaternionic manifold (M,P) of dimension bigger or equal to eight, in terms of the integrability of two or three sections of the…

Differential Geometry · Mathematics 2008-08-19 Liana David

The symmetry dimension of a geometric structure is the dimension of its symmetry algebra. We investigate symmetries of almost quaternionic structures of quaternionic dimension $n$. The maximal possible symmetry is realized by the…

Differential Geometry · Mathematics 2016-07-08 Boris Kruglikov , Henrik Winther , Lenka Zalabova

We construct examples of complete quaternionic K\"ahler manifolds with an end of finite volume, which are not locally homogeneous. The manifolds are aspherical with fundamental group which is up to an infinite cyclic extension a semi-direct…

Differential Geometry · Mathematics 2022-12-23 V. Cortés , M. Röser , D. Thung

We prove that any $4$-dimensional almost-K\"ahler Lie algebra of constant Hermitian holomorphic sectional curvature with respect to the canonical Hermitian connection is K\"ahler.

Differential Geometry · Mathematics 2017-09-27 Mehdi Lejmi , Luigi Vezzoni

We construct explicit left invariant quaternionic contact structures on Lie groups with zero and non-zero torsion, and with non-vanishing quaternionic contact conformal curvature tensor, thus showing the existence of quaternionic contact…

Differential Geometry · Mathematics 2009-09-30 Luis C. de Andres , Marisa Fernandez , Stefan Ivanov , Jose A. Santisteban , Luis Ugarte , Dimiter Vassilev

We study the problem of existence of geometric structures on compact complex surfaces that are related to split quaternions. These structures, called para-hypercomplex, para-hyperhermitian and para-hyperk\"ahler are analogs of the…

Differential Geometry · Mathematics 2015-06-05 Johann Davidov , Gueo Grantcharov , Oleg Mushkarov , Miroslav Yotov

We classify six-dimensional homogeneous nearly K\"{a}hler manifolds and give a positive answer to Gray and Wolf's conjecture: every homogeneous nearly K\"{a}hler manifold is a Riemannian 3-symmetric space equipped with its canonical almost…

Differential Geometry · Mathematics 2007-05-23 Jean-Baptiste Butruille

We study curvature properties of four-dimensional almost Hermitian manifolds with vanishing Bochner curvature tensor as defined by Tricerri and Vanhecke. We give local structure theorems for such Kaehler manifolds, and find out several…

Differential Geometry · Mathematics 2007-10-11 Y. Euh , J. Lee , J. H. Park , K. Sekigawa , A. Yamada

We investigate the integrability of natural almost complex structures on the twistor space of an almost para-quaternionic manifold as well as the integrability of natural almost paracomplex structures on the reflector space of an almost…

Differential Geometry · Mathematics 2007-05-23 Stefan Ivanov , Ivan Minchev , Simeon Zamkovoy

We will discuss in this paper homogeneous locally conformally Keahler (or shortly homogeneous l.c.K.) manifolds and locally homogeneous l.c.K. manifolds from various aspects of study in the field of l.c.K. geometry. We will provide a survey…

Differential Geometry · Mathematics 2016-01-19 Keizo Hasegawa , Yoshinobu Kamishima

We investigate a class of locally conformal almost K\"ahler structures and prove that, under some conditions, this class is a subclass of almost K\"ahler structures. We show that a locally conformal almost K\"ahler manifold admits a…

General Mathematics · Mathematics 2021-04-02 Ntokozo Sibonelo Khuzwayo , Fortuné Massamba

Mixed 3-structures are odd-dimensional analogues of paraquaternionic structures. They appear naturally on lightlike hypersurfaces of almost paraquaternionic hermitian manifolds. We study invariant and anti-invariant submanifolds in a…

Differential Geometry · Mathematics 2020-07-30 Stere Ianus , Liviu Ornea , Gabriel Eduard Vilcu

A para-K\"ahler manifold can be defined as a pseudo-Riemannian manifold $(M,g)$ with a parallel skew-symmetric para-complex structures $K$, i.e. a parallel field of skew-symmetric endomorphisms with $ K^2 = \mathrm{Id} $ or, equivalently,…

Differential Geometry · Mathematics 2008-12-23 Dmitri V. Alekseevsky , Costantino Medori , Adriano Tomassini