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On a manifold with an almost contact metric structure $(\varphi,\vec\xi,\eta,g,X,D)$ the notions of the interior and the $N$-prolonged connections are introduced. Using the $N$-prolonged connection, a new almost contact metric structure is…

Differential Geometry · Mathematics 2015-06-08 Sergey V. Galaev

The aim of this paper is to study self-similar solutions to the symplectic cuvature flow on 6-dimensional nilmanifolds. For this purpose, we focus our attention in the family of symplectic Two- and Three-step nilpotent Lie algebras…

Differential Geometry · Mathematics 2015-03-13 Edison Alberto Fernández-Culma

We obtain a class of locally symetric Kaehler Einstein structures on the nonzero cotangent bundle of a Riemannian manifold of positive constant sectional curvature. The obtained class of Kaehler Einstein structures depends on one essential…

Differential Geometry · Mathematics 2007-05-23 D. D. Porosniuc

In this paper, left-invariant almost contact metric structures on three-dimensional non-unimodular Lie groups are investigated. It is proved that for every Riemannian Lie group, there is one of these structures. In addition, left-invariant…

Differential Geometry · Mathematics 2020-02-12 Pejhman Vatandoost-Miandehi , A. Razavi

We define an almost--cosymplectic--contact structure which generalizes cosymplectic and contact structures of an odd dimensional manifold. Analogously, we define an almost--coPoisson--Jacobi structure which generalizes a Jacobi structure.…

Differential Geometry · Mathematics 2008-01-10 Josef Janyška , Marco Modugno

These notes on Riemannian geometry use the bases bundle and frame bundle, as in Geometry of Manifolds, to express the geometric structures. It has more problems and omits the background material. It starts with the definition of Riemannian…

Differential Geometry · Mathematics 2013-07-30 Richard L. Bishop

We study manifolds endowed with an (almost) even Clifford (hermitian) structure and admitting a large automorphism group. We classify them when they are simply connected and the dimension of the automorphism group is maximal, and also prove…

Differential Geometry · Mathematics 2016-06-07 Gerardo Arizmendi , Rafael Herrera , Noemi Santana

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

In this paper, we systematically compute the Bianchi identities for the canonical connection on an almost Hermitian manifold. Moreover, we also compute the curvature tensor of the Levi-Civita connection on almost Hermitian manifolds in…

Differential Geometry · Mathematics 2018-12-14 Chengjie Yu

The well-known K\"ahler identities naturally extend to the non-integrable setting. This paper deduces several geometric and topological consequences of these extended identities for compact almost K\"ahler manifolds. Among these are…

Differential Geometry · Mathematics 2020-05-22 Joana Cirici , Scott O. Wilson

Starting from a cubic form, we give a general construction of a quasi-complete homogeneous manifold endowed with a natural contact structure. We show that it can be compactified into a projective contact manifold if and only if the cubic…

Algebraic Geometry · Mathematics 2008-12-22 Jun-Muk Hwang , Laurent Manivel

We realize specific classical symmetric spaces, like the semi-K\"ahler symmetric spaces discovered by Berger, as cotangent bundles of symmetric flag manifolds. These realizations enable us to describe these cotangent bundles' geodesics and…

Differential Geometry · Mathematics 2024-03-19 Leonardo F. Cavenaghi , Carolina Garcia , Lino Grama , Luiz San Martin

We introduce the concept of generalized almost plastic structure, and, on a pseudo-Riemannian manifold endowed with two $(1,1)$-tensor fields satisfying some compatibility conditions, we construct a family of generalized almost plastic…

Differential Geometry · Mathematics 2024-11-21 Adara M. Blaga , Antonella Nannicini

In a preceding paper we introduced a notion of compatibility between a Jacobi structure and a Riemannian structure on a smooth manifold. We proved that in the case of fundamental examples of Jacobi structures : Poisson structures, contact…

Differential Geometry · Mathematics 2019-11-13 Yacine Aït Amrane , Ahmed Zeglaoui

We study almost contact metric structures induced by 2-fold vector cross products on manifolds with $G_2$ structures. We get some results on possible classes of almost contact metric structures. Finally we give examples.

Differential Geometry · Mathematics 2016-01-08 Nülifer Özdemir , Mehmet Solgun , Şirin Aktay

We give simple characterizations of contact 1-forms in terms of Dirac structures. We also relate normal almost contact structures to the theory of Dirac structures.

Differential Geometry · Mathematics 2016-08-16 David Iglesias-Ponte , Aïssa Wade

We prove that a compact contact threefold which is bimeromorphically equivalent to a Kaehler manifold and not rationally connected is the projectivised tangent bundle of a Kaehler surface.

Algebraic Geometry · Mathematics 2010-05-11 Kristina Frantzen , Thomas Peternell

This is a survey about certain "almost homomorphisms" and "almost linear" functionals (called quasi-morphisms and quasi-states) in symplectic topology and their applications to Hamiltonian dynamics, functional-theoretic properties of…

Symplectic Geometry · Mathematics 2014-12-24 Michael Entov

We consider certain fiber bundles over a paraquaternionic contact manifolds, called twistor and reflector spaces, and show that these carry an intrinsic geometric structure that is always integrable.

Differential Geometry · Mathematics 2024-09-04 Stefan Ivanov , Ivan Minchev , Marina Tchomakova

In the paper there are described new examples of conformally flat three dimensional almost cosymplectic manifolds. All these manifolds form a class which was completely characterized.

Differential Geometry · Mathematics 2007-10-05 Piotr Dacko