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Main interest of the present paper is to investigate the almost {\alpha}-cosymplectic manifolds for which the characteristic vector field of the almost {\alpha}-cosymplectic structure satisfies a specific ({\kappa},{\mu},{\nu})-nullity…

Differential Geometry · Mathematics 2010-07-06 Hakan Öztürk , Nesip Aktan , Cengizhan Murathan

In this paper, we construct complex metric structures on complex hypersurfaces in hyperkahler manifolds. This construction is that in contact geometry.

Differential Geometry · Mathematics 2015-11-04 Mitsuhiro Imada

On a Riemannian almost product manifold $(M,P,g)$ we consider a linear connection preserving the almost product structure $P$ and the Riemannian metric $g$ and having a totally skew-symmetric torsion. We determine the class of the manifolds…

Differential Geometry · Mathematics 2012-05-08 Dimitar Mekerov , Mancho Manev

In this work, we prove that every complex contact structure gives rise to a distinguished type of almost contact metric 3-structure. As an application of our main result, we provide several new examples of manifolds which admit taut contact…

Differential Geometry · Mathematics 2020-09-24 Eder M. Correa

We classify locally homogeneous quasi-Sasakian manifolds in dimension five that admit a parallel spinor $\psi$ of algebraic type $F \cdot \psi = 0$ with respect to the unique connection $\nabla$ preserving the quasi-Sasakian structure and…

Differential Geometry · Mathematics 2007-05-23 Thomas Friedrich , Stefan Ivanov

We introduce a new type of slant curves in almost contact B-metric manifolds, called $\varphi $-slant curves, by an additional condition which is specific for these manifolds. In this paper we study $\varphi $-slant null curves in a class…

Differential Geometry · Mathematics 2020-05-13 Galia Nakova

Our aim in this paper is to give some examples of $(a, 1)f$ Riemannian structures (a generalization of an $r$-paracontact structure) induced on product of spheres of codimension $r$ ($r \in \{1,2\} $) in an $m$-dimensional Euclidean space…

Differential Geometry · Mathematics 2007-11-06 Cristina-Elena Hretcanu , Mircea Crasmareanu

In this article we give a classification of three dimensional m-quasi Einstein manifolds with two distinct Ricci-eigen values. Our study provides explicit description of local and complete metrics and potential functions. We also describe…

Differential Geometry · Mathematics 2017-12-12 Jongsu Kim , Jinwoo Shin

We study the relations between the projective and the almost conformally symplectic structures on a smooth even dimensional manifold. We describe these relations by a single almost conformally symplectic connection with totally trace--free…

Differential Geometry · Mathematics 2017-10-17 Jan Gregorovič

In the present work, we introduce a linear connection (preserving the almost product structure and the Riemannian metric) on Riemannian almost product manifolds. This connection, called P-connection, is an analogue of the first canonical…

Differential Geometry · Mathematics 2011-01-24 Dimitar Mekerov

In this work, we revisit quasi-Sasakian geometry in dimension three and examine how these structures interact with the foliation generated by the Reeb vector field and its basic cohomology. Through a deformation-based approach, we show that…

Differential Geometry · Mathematics 2025-12-29 Emmanuel Gnandi , Fortuné Massamba

In this paper we have studied pseudosymmetric, Ricci-pseudosymmetric and projectively pseudosymmetric para-Sasakian manifold admitting a quarter-symmetric metric connection and constructed examples of 3-dimensional and 5-dimensional…

General Mathematics · Mathematics 2019-01-24 Vishnuvardhana. S. V. , Venkatesha

In this paper the notion of quasi-isometry between two Riemannian manifolds has been introduced. This idea is also imposed to study quasi-isometry between two almost contact metric manifolds. Moving further, some curvature properties of two…

Differential Geometry · Mathematics 2025-11-03 Arindam Bhattacharyya , Dipen Ganguly , Paritosh Ghosh , Sumanjit Sarkar

A 3D almost-Riemannian manifold is a generalized Riemannian manifold defined locally by 3 vector fields that play the role of an orthonormal frame, but could become collinear on some set $\Zz$ called the singular set. Under the Hormander…

Optimization and Control · Mathematics 2014-07-03 Ugo Boscain , Grégoire Charlot , Moussa Gaye , Paolo Mason

The subject of investigations are the almost hypercomplex manifolds with Hermitian and anti-Hermitian (Norden) metrics. A linear connection D is introduced such that the structure of these manifolds is parallel with respect to D and its…

Differential Geometry · Mathematics 2012-05-08 Mancho Manev , Kostadin Gribachev

This paper is devoted to the study of curvature and torsion of almost contact curves in trans-Sasakian 3-Manifolds. The conditions for the frenet curves to be almost contact curves in trans-Sasakian 3-manifolds have been obtained.

Differential Geometry · Mathematics 2014-01-27 S. K. Srivastava

In this paper we study slant submanifolds of Lorentzian almost contact manifolds. We have taken the submanifold as a space like and then defined the slant angle on a submanifold and thus we extended the results of A. Lotta (Slant…

Differential Geometry · Mathematics 2012-04-30 Khushwant Singh , Siraj Uddin , Satvinder Singh Bhatia , M. A. Khan

The notion of \emph{contact triad connection} on contact triads $(Q,\lambda,J_\xi)$ was introduced by Wang and the present author in early 2010's from scratch as the contact analog to the canonical connection of an almost K\"ahler…

Differential Geometry · Mathematics 2026-01-01 Yong-Geun Oh

In 1990, D. Chinea and C. Gonzalez gave a classification of almost contact metric manifolds into $2^{12}$ classes, based on the behaviour of the covariant derivative $\nabla^g\Phi$ of the fundamental $2$-form $\Phi$. This large number makes…

Differential Geometry · Mathematics 2026-01-21 Ilka Agricola , Dario Di Pinto , Giulia Dileo , Marius Kuhrt

Let $(\varphi_\alpha,\xi_\alpha,g)$ for $\alpha=1,2$, and $3$ be a contact metric $3$-structure on the manifold $M^{4n+3}$. We show that the $3$-contact distribution of this structure admits a HyperKahler structure whenever…

Differential Geometry · Mathematics 2023-04-26 Hassan Attarchi , Fatemeh Babaei