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We classify, up to a local isometry, all non-Kahler almost Kahler 4-manifolds for which the fundamental 2-form is an eigenform of the Weyl tensor, and whose Ricci tensor is invariant with respect to the almost complex structure.…

Differential Geometry · Mathematics 2007-05-23 Vestislav Apostolov , John Armstrong , Tedi Draghici

It was recently shown that under mild assumptions second-order conformally superintegrable systems can be encoded in a $(0,3)$-tensor, called structure tensor. For abundant systems, this approach led to algebraic integrability conditions…

Differential Geometry · Mathematics 2025-04-08 Vicente Cortés , Andreas Vollmer

We extend the notion of "coupling with a foliation" from Poisson to Dirac structures and get the corresponding generalization of the Vorobiev characterization of coupling Poisson structures. We show that any Dirac structure is coupling with…

Symplectic Geometry · Mathematics 2007-05-23 Izu Vaisman

Let $f: Y\to X$ be a morphism between smooth complex quasi-projective varieties and $Z$ be the closure of $f(Y)$ with $\iota: Z\to X$ the inclusion map. We prove that a. for any field $K$, there exist finitely many semisimple…

Algebraic Geometry · Mathematics 2023-11-23 Ya Deng , Yuan Liu

Our aim is to define and study a structure for some $(4n+3)$-dimensional manifolds which is named almost coquaternion structure. This structure is composed of three almost cocomplex structures $(\phi_a, \xi_a, \eta_a)$, $a = 1,2,3$, which…

Differential Geometry · Mathematics 2015-10-19 Constantin Udriste

We provide models that are as close as possible to being formal for a large class of compact manifolds that admit a transversely Kaehler structure, including Vaisman and quasi-Sasakian manifolds. As an application we are able to classify…

Differential Geometry · Mathematics 2022-03-18 Beniamino Cappelletti-Montano , Antonio De Nicola , Juan Carlos Marrero , Ivan Yudin

Let $(M^{n},g)$ be a closed, connected, oriented, $C^{\infty}$, Riemannian, n-manifold with a transversely oriented foliation $\boldkey F$. We show that if $\lbrace X,Y \rbrace$ are basic vector fields, the leaf component of $[X,Y]$,…

Differential Geometry · Mathematics 2007-05-23 Gabriel Baditoiu , Richard H. Escobales , Stere Ianus

In this paper, metallic structure and almost quadratic metric phi-structure are studied. Based on metallic (polynomial) Riemannian manifold, Kenmotsu quadratic metric manifold, cosymplectic quadratic metric manifold are defined and gave…

General Mathematics · Mathematics 2018-12-31 Sinem Gönül , İrem Küpeli Erken , Aziz Yazla , Cengizhan Murathan

Semiclassical limits of generic multiparameter quantized coordinate rings A = O_q(k^n) of affine spaces are constructed and related to A, for k an algebraically closed field of characteristic zero and q a multiplicatively antisymmetric…

Quantum Algebra · Mathematics 2008-02-08 K. R. Goodearl , E. S. Letzter

We characterize quasi K\"ahler manifolds whose curvature tensor associated to the canonical Hermitian connection satisfies the first Bianchi identity. This condition is related with the third Gray identity and in the almost K\"ahler case…

Differential Geometry · Mathematics 2011-01-11 Antonio J. Di Scala , Luigi Vezzoni

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

A surjective submersion $\pi : M \to B$ carrying a field of simplectic structures on the fibres is symplectic if this Poisson structure is minimal. A symplectic submersion may be interpreted as a family of mechanical systems depending on a…

dg-ga · Mathematics 2008-02-03 F. Alcalde Cuesta

We look at Poisson geometry taking the viewpoint of singular foliations, understood as suitable submodules generated by Hamiltonian vector fields rather than partitions into (symplectic) leaves. The class of Poisson structures which behave…

Symplectic Geometry · Mathematics 2017-03-21 Iakovos Androulidakis , Marco Zambon

We consider Courant and Courant-Jacobi brackets on the stable tangent bundle $TM\times\mathds{R}^h$ of a differentiable manifold and corresponding Dirac, Dirac-Jacobi and generalized complex structures. We prove that Dirac and Dirac-Jacobi…

Differential Geometry · Mathematics 2007-05-23 Izu Vaisman

A general model for geometric structures on differentiable manifolds is obtained by deforming infinitesimal symmetries. Specifically, this model consists of a Lie algebroid, equipped with an affine connection compatible with the Lie…

Differential Geometry · Mathematics 2012-03-07 Anthony D. Blaom

The interest of geometers in $f$-structures is motivated by the study of the dynamics of contact foliations, as well as their applications in physics. A weak $f$-structure on a smooth manifold, introduced by V. Rovenski and R. Wolak (2022),…

Differential Geometry · Mathematics 2025-08-13 Sourav Nayak , Dhriti Sundar Patra , Vladimir Rovenski

We recall the notion of a singular foliation (SF) on a manifold $M$, viewed as an appropriate submodule of $\mathfrak{X}(M)$, and adapt it to the presence of a Riemannian metric $g$, yielding a module version of a singular Riemannian…

Differential Geometry · Mathematics 2024-12-31 Hadi Nahari , Thomas Strobl

On the generalized tangent bundle of a smooth manifold, we study skew-symmetric endomorphism satisfying an arbitrary polynomial equation with real constant coefficients. We study the compatibility of these structures with the de Rham…

Differential Geometry · Mathematics 2022-12-29 Marco Aldi , Daniele Grandini

We apply the general theory of codimension one integrability conditions for $G$-structures developed in arXiv:1306.6817v3 [math.DG] to the case of quaternionic CR geometry. We obtain necessary and sufficient conditions for an almost CR…

Differential Geometry · Mathematics 2017-04-10 Andrea Santi

A generalized complex manifold is locally gauge-equivalent to the product of a holomorphic Poisson manifold with a real symplectic manifold, but in possibly many different ways. In this paper we show that the isomorphism class of the…

Symplectic Geometry · Mathematics 2017-12-06 Michael Bailey , Marco Gualtieri