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As a generalization of Riemannian submersions, horizontally conformal submersions, semi-invariant submersions, h-semi-invariant submersions, almost h-semi-invariant submersions, conformal semi-invariant submersions, we introduce h-conformal…

Differential Geometry · Mathematics 2017-08-28 Kwang-Soon Park

We obtain a local classification of complex homothetic foliations on Kaehler manifolds by complex curves. This is used to construct almost Kaehler, Ricci-flat metrics subject to additional curvature properties.

Differential Geometry · Mathematics 2012-06-18 Simon G. Chiossi , Paul-Andi Nagy

Some geometric structures with associated Riemannian metrics have been considered in the book.

Differential Geometry · Mathematics 2008-05-23 Alexander A. Ermolitsky

Following our approach to metric Lie algebras developed in math.DG/0312243 we propose a way of understanding pseudo-Riemannian symmetric spaces which are not semi-simple. We introduce cohomology sets (called quadratic cohomology) associated…

Differential Geometry · Mathematics 2007-05-23 Ines Kath , Martin Olbrich

We characterise the existence of balanced and pluriclosed metrics on compact quotients of real semisimple Lie groups equipped with regular complex structures, in terms of Vogan diagrams. Consequently, such complex manifolds cannot…

Differential Geometry · Mathematics 2026-04-29 Joseph Kwong

Almost paracontact Riemannian manifolds of the lowest dimension are studied, whose paracontact distributions are equipped with an almost paracomplex structure. These manifolds are constructed as a product of a real line and a 2-dimensional…

Differential Geometry · Mathematics 2023-09-06 Mancho Manev , Veselina Tavkova

In the present article the geometry of semi-Riemannian manifolds with nonholonomic constraints is studied. These manifolds can be considered as analogues to the sub-Riemannian manifolds, where the positively definite metric is substituted…

Differential Geometry · Mathematics 2009-01-13 Anna Korolko , Irina Markina

We prove that a compact Vaisman manifold $(M, J)$ cannot admit some type of special Hermitian metrics, such as special $k$-Gauduchon metrics, $p$-K\"ahler forms, Hermitian-symplectic or strongly Gauduchon metrics compatible to the same…

Differential Geometry · Mathematics 2023-06-08 Daniele Angella , Alexandra Otiman

On $4$-symmetric symplectic spaces, invariant almost complex structures -- up to sign -- arise in pairs. We exhibit some $4$-symmetric symplectic spaces, with a pair of "natural" compatible (usually not positive) invariant almost complex…

Differential Geometry · Mathematics 2022-06-14 Michel Cahen , Simone Gutt , Manar Hayyani , Mohammed Raouyane

We develop a theory of large scale geometry of metrisable topological groups that, in a significant number of cases, allows one to define and identify a unique quasi-isometry type intrinsic to the topological group. Moreover, this…

Group Theory · Mathematics 2014-03-14 Christian Rosendal

We ask a general question: what are locally homogeneous compact pseudo-Riemannian Einstein manifolds? We show that any standard compact Clifford-Klein form of a simple non-compact Lie group admits at least one Einstein metric. We conjecture…

Differential Geometry · Mathematics 2020-06-17 Maciej Bochenski , Aleksy Tralle

We first investigate the geometry of orbits of the isotropy action on a semi-simple pseudo-Riemannian symmetric space by investigating the complexified action. Next we investigate the geometry of the orbits of Hermann type actions on the…

Differential Geometry · Mathematics 2011-02-25 Naoyuki Koike

This note is a continuation of the paper [2] (see references). We describe some natural pseudogroup structures on almost complex manifolds of type $m$. A kind of coherency is discussed for the sheaf of almost holomorphic functions.

Complex Variables · Mathematics 2007-05-23 S. Dimiev

In this work we study riemannian metrics on flag manifolds adapted to the symmetries of these homogeneous nonsymmetric spaces. We first introduce the notion of riemannian $\Gamma $-symmetric space when $\Gamma $ is a general abelian finite…

Differential Geometry · Mathematics 2007-05-23 Abelkader Bouyakoub , Michel Goze , Elisabeth Remm

Any homogeneous expanding Ricci soliton is known to be isometric to a Lie subgroup of the solvable part of the Iwasawa decomposition associated with a symmetric space of non-compact type, with the metric induced as a submanifold. In this…

Differential Geometry · Mathematics 2024-07-10 Ángel Cidre-Díaz , Víctor Sanmartín-López

Let $(\acute{N},g,\nabla )$\ be a $2n$-dimensional quasi-statistical manifold that admits a pseudo-Riemannian metric $g$ (or $h)$ and a linear connection $\nabla $ with torsion. This paper aims to study an almost Hermitian structure $(g,L)$…

Differential Geometry · Mathematics 2023-07-31 Aydin Gezer , Busra Aktas , Olgun Durmaz

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 define harmonic maps between sub-Riemannian manifolds by generalizing known definitions for Riemannian manifolds. We establish conditions for when a horizontal map into a Lie group with a left-invariant metric structure is a harmonic…

Differential Geometry · Mathematics 2023-08-23 Erlend Grong , Irina Markina

We extend the Newlander-Nirenberg theorem to manifolds with almost complex structures that have somewhat less than Lipschitz regularity. We also discuss the regularity of local holomorphic coordinates in the integrable case, with particular…

Differential Geometry · Mathematics 2007-11-08 C. Denson Hill , Michael Taylor

In this work, we study metrics which are both homogeneous and Ricci soliton. If there exists a transitive solvable group of isometries on a Ricci soliton, we show that it is isometric to a solvsoliton. Moreover, unless the manifold is flat,…

Differential Geometry · Mathematics 2013-04-26 Michael Jablonski