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We call a foliation $\mathcal{F}$ on a compact manifold infinitesimally rigid if its deformation cohomology $H^{1}(\mathcal{F},N\mathcal{F})$ vanishes. This paper studies infinitesimal rigidity for a distinguished class of Riemannian…

Differential Geometry · Mathematics 2025-02-03 Stephane Geudens , Florian Zeiser

Let G be a noncompact real semisimple Lie group. The regular coadjoint orbits of G can be partitioned into a finite set of types. We show that on each regular orbit, the Iwasawa decomposition induces a left-invariant foliation which is…

Symplectic Geometry · Mathematics 2011-10-24 William D. Kirwin

We determine the structure of the fundamental group of the regular leaves of a closed singular Riemannian foliation on a compact, simply connected Riemannian manifold. We also study closed singular Riemannian foliations whose leaves are…

Differential Geometry · Mathematics 2015-06-12 Fernando Galaz-Garcia , Marco Radeschi

In this paper, we study stability for harmonic foliations on locally conformal K\"ahler manifolds with complex leaves. We also discuss instability for harmonic foliations on compact submanifolds immersed in Euclidean spaces and compact…

Differential Geometry · Mathematics 2007-05-23 K. Ichikawa , T. Noda

We classify the harmonic morphisms with one-dimensional fibres (1) from real-analytic conformally-flat Riemannian manifolds of dimension at least four, and (2) between conformally-flat Riemannian manifolds of dimensions at least three.

Differential Geometry · Mathematics 2007-05-23 Radu Pantilie

We study the geometry of a family of Lie groups, which contained the classical affine Lie groups, endowed with an exact left invariant symplectic form. We show that this family is closed by symplectic reduction and symplectic double…

Differential Geometry · Mathematics 2016-08-16 Jean Michel Dardie , Alberto Medina , Hassène Siby

We describe a local model for any Singular Riemannian Foliation in a neighbourhood of a closed saturated submanifold of a regular stratum. Moreover we construct a Lie groupoid which controls the transverse geometry of the linear…

Differential Geometry · Mathematics 2021-03-08 Marcos M. Alexandrino , Marcelo K. Inagaki , Mateus de Melo , Ivan Struchiner

Deformation of morphisms along leaves of foliations define the tangential foliation on the corresponding space of morphisms. We prove that codimension one fo-liations having a tangential foliation with at least one non-algebraic leaf are…

Classical Analysis and ODEs · Mathematics 2021-02-23 Frank Loray , Jorge Pereira , Frédéric Touzet

In this paper we study the Lie groupoids which appear in foliation theory. A foliation groupoid is a Lie groupoid which integrates a foliation, or, equivalently, whose anchor map is injective. The first theorem shows that, for a Lie…

K-Theory and Homology · Mathematics 2007-05-23 M. Crainic , I. Moerdijk

It is well-known that any isotopically connected diffeomorphism group $G$ of a manifold determines uniquely a singular foliation $\F_G$. A one-to-one correspondence between the class of singular foliations and a subclass of diffeomorphism…

Differential Geometry · Mathematics 2011-03-21 Tomasz Rybicki

This is a survey concerning the relationship between Lie Groupoids (and their morphisms) and singular foliations in the sense of Sussmann-Stefan (considered from a purely geometrical point of view). We focus on the interaction between the…

Geometric Topology · Mathematics 2007-11-16 Jean Pradines

A foliation $(M,\mathcal{F})$ is said to be $2$--calibrated if it admits a closed 2-form $\omega$ making each leaf symplectic. By using approximately holomorphic techniques, a sequence $W_k$ of $2$--calibrated submanifolds of…

Differential Geometry · Mathematics 2018-07-31 David Martínez Torres , Álvaro del Pino , Francisco Presas

Equivalences between conformal foliations on Euclidean $3$-space, Hermitian structures on Euclidean $4$-space, shear-free ray congruences on Minkowski $4$-space, and holomorphic foliations on complex $4$-space are explained geometrically…

dg-ga · Mathematics 2008-02-03 P. Baird , J. C. Wood

Let $\mathcal{F}$ be a transversely orientable codimension one minimal foliation without vanishing cycles of a manifold $M$. We show that if the fundamental group of each leaf of $\mathcal{F}$ has polynomial growth of degree $k$ for some…

Geometric Topology · Mathematics 2017-07-19 Tomoo Yokoyama

We study left-invariant conformal Killing $2$- or $3$-forms on simply connected $2$-step nilpotent Riemannian Lie groups. We show that if the center of the group is of dimension greater than or equal to 4, then every such form is…

Differential Geometry · Mathematics 2023-05-02 Viviana del Barco , Andrei Moroianu

We discuss possible notions of conformal Lie algebras, paying particular attention to graded conformal Lie algebras with $d$-dimensional space isotropy: namely, those with a $\mathfrak{co}(d)$ subalgebra acting in a prescribed way on the…

High Energy Physics - Theory · Physics 2019-02-20 José M. Figueroa-O'Farrill

We study 4-dimensional Riemannian manifolds equipped with a minimal and conformal foliation $\mathcal F$ of codimension 2. We prove that the two adapted almost Hermitian structures $J_1$ and $J_2$ are both cosymplectic if and only if…

Differential Geometry · Mathematics 2014-09-04 Sigmundur Gudmundsson

In this work, we find an equation that relates the Ricci curvature of a riemannian manifold $M$ and the second fundamental forms of two orthogonal foliations of complementary dimensions, $\mathcal{F}$ and $\mathcal{F}^{\bot}$, defined on…

Differential Geometry · Mathematics 2017-11-16 André de Oliveira Gomes , Eurípedes Carvalho da Silva

A class of codimension one foliations has been recently introduced by imposing a natural compatibility condition with a closed maximally non-degenerate 2-form. In this paper we study for such foliations the information captured by a…

Differential Geometry · Mathematics 2018-07-31 D. Martinez Torres

In this article, we study the geometric properties of codimension one foliations on Riemannian manifolds equipped with vector fields that are closed and conformal. Apart from its singularities, these vector fields define codimension one…

Differential Geometry · Mathematics 2024-07-08 Euripedes da Silva , Ícaro Gonçalves , Júlio Pereira