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Dirac structures are geometric objects that generalize both Poisson structures and presymplectic structures on manifolds. They naturally appear in the formulation of constrained mechanical systems. In this paper, we show that the evolution…

Mathematical Physics · Physics 2018-02-14 François Gay-Balmaz , Hiroaki Yoshimura

We first recall some basic definitions and facts about Jacobi manifolds, generalized Lie bialgebroids, generalized Courant algebroids and Dirac structures. We establish an one-one correspondence between reducible Dirac structures of the…

Symplectic Geometry · Mathematics 2007-05-23 Fani Petalidou , Joana M. Nunes da Costa

We study regular contact manifolds $(M,\eta)$ whose Reeb vector field is complete and prove that they are canonically principal bundles with the structure group $S^1$ or $\mathbb{R}$. For compact $M$, our proof is very short and elementary…

Symplectic Geometry · Mathematics 2024-12-31 Katarzyna Grabowska , Janusz Grabowski

We establish the conditions for the induced generalized metric F structure of an oriented hypersurface of a generalized K\"ahler manifold to be a generalized CRFK structure. Then, we discuss a notion of generalized almost contact structure…

Differential Geometry · Mathematics 2017-11-23 Izu Vaisman

Generalised almost complex structures $\mathcal J$ on transitive Courant algebroids $E$ are studied in terms of their components with respect to a splitting $E\cong TM \oplus T^*M \oplus \mathcal G$, where $M$ denotes the base of $E$ and…

Differential Geometry · Mathematics 2025-12-12 Vicente Cortés , Liana David

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 discuss in this note two dual canonical operations on Dirac structures $L$ and $R$ -- the \emph{tangent product} $L \star R$ and the \emph{cotangent product} $L \circledast R$. Our first result gives an explicit description of the leaves…

Symplectic Geometry · Mathematics 2025-04-17 Pedro Frejlich , David Martínez Torres

This is a survey article on a known generalization of Dirac-type operators to transverse operators called basic Dirac operators on Riemannian foliations, which are smooth foliations that have a transverse geometric structure. Construction…

Differential Geometry · Mathematics 2009-09-01 Ken Richardson

A Dirac structure is a Lagrangian subbundle of a Courant algebroid, $L\subset\mathbb{E}$, which is involutive with respect to the Courant bracket. In particular, $L$ inherits the structure of a Lie algebroid. In this paper, we introduce the…

Differential Geometry · Mathematics 2014-08-25 David Li-Bland

We examine the standard Courant bracket and its extensions, defined by twists with different $O(D,D)$ transformations relevant to string theory. We analyze Dirac structures on these Courant algebroids and derive the constraints they impose…

High Energy Physics - Theory · Physics 2025-02-07 Ilija Ivanišević , Branislav Sazdović

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

In this paper, we propose the concept of $(\pm)$-discrete Dirac structures over a manifold, where we define $(\pm)$-discrete two-forms on the manifold and incorporate discrete constraints using $(\pm)$-finite difference maps. Specifically,…

Mathematical Physics · Physics 2025-11-19 Linyu Peng , Hiroaki Yoshimura

Cosymplectic and normal almost contact structures are analogues of symplectic and complex structures that can be defined on 3-manifolds. Their existence imposes strong topological constraints. Generalized geometry offers a natural common…

Differential Geometry · Mathematics 2026-05-21 Joan Porti , Roberto Rubio

We describe Dirac structures on surfaces and 3-manifolds. Every Dirac structure on a surface $M$ is described either by a regular 1-foliation or by a section of a circle bundle obtained as a fiberwise compactification of the line bundle…

Symplectic Geometry · Mathematics 2017-12-08 Geoffrey Scott

We look at generalized complex structures from the point of view of Poisson and Dirac geometry and we remark that the puzzling equations underlying the notion of generalized complex structure have miraculously simple meaning when passing to…

Differential Geometry · Mathematics 2007-05-23 Marius Crainic

We study precontact groupoids whose infinitesimal counterparts are Dirac-Jacobi structures. These geometric objects generalize contact groupoids. We also explain the relationship between precontact groupoids and homogeneous presymplectic…

Differential Geometry · Mathematics 2009-11-11 David Iglesias Ponte , Aissa Wade

We study a new kind of Courant algebroid on Poisson manifolds, which is a variant of the generalized tangent bundle in the sense that the roles of tangent and the cotangent bundle are exchanged. Its symmetry is a semidirect product of…

High Energy Physics - Theory · Physics 2015-08-25 T. Asakawa , H. Muraki , S. Sasa , S. Watamura

We determine the Hamiltonian vector field on an odd dimensional manifold endowed with almost cosymplectic structure. This is a generalization of the corresponding Hamiltonian vector field on manifolds with almost transitive contact…

Differential Geometry · Mathematics 2022-11-23 Stefan Berceanu

The concept of a Dirac algebroid, which is a linear almost Dirac structure on a vector bundle, was designed to generate phase equations for mechanical systems with linear nonholonomic constraints. We apply it to systems with magnetic-like…

Mathematical Physics · Physics 2025-05-01 Katarzyna Grabowska , Michalina Borczyńska , Joanna Majsak , Tomasz Sobczak

We introduce generalized almost contact structures which admit the $B$-field transformations on odd dimensional manifolds. We provide definition of generalized Sasakain structures from the view point of the generalized almost contact…

Differential Geometry · Mathematics 2012-12-27 Ken'ichi Sekiya