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We consider classes of noncompact n-folds with trivial canonical bundle, that are linear foliations on nonsingular projective varieties, in general without a projection to the base. We obtain them as first-order deformations of total spaces…

Algebraic Geometry · Mathematics 2007-12-05 Antonio Ricco

The study of global deformations of Lie algebras is related to the problem of classification of simple Lie algebras over fields of small characteristic. The classification of finite-dimensional simple Lie algebras is complete over…

Rings and Algebras · Mathematics 2020-12-29 Natalya Chebochko

We consider a class of singular foliations in the sense of Androulidakis and Skandalis that we call transverse order $k$ foliations. These have a finite number of leaves: one hypersurface (the singular leaf) together with the components of…

Operator Algebras · Mathematics 2024-02-09 Michael Francis

We refine the cyclic cohomological apparatus for computing the Hopf cyclic cohomology of the Hopf algebras associated to infinite primitive Cartan-Lie pseudogroups, and for the transfer of their characteristic classes to foliations. The…

Quantum Algebra · Mathematics 2011-02-16 Henri Moscovici , Bahram Rangipour

Let X be a compact complex surface with a real foliation. If all leaves are compact complex curves, the foliation must be holomorphic.

Complex Variables · Mathematics 2007-05-23 Joerg Winkelmann

Let $\mathcal{F}$ be a foliation on a projective manifold $X$ with $-K_{\mathcal{F}}$ nef. Assume that either $\mathcal{F}$ is regular, or it has a compact leaf. We prove that there is a locally trivial fibration $f\colon X\to Y$, and a…

Algebraic Geometry · Mathematics 2023-06-22 Wenhao Ou

In this paper, we characterize the second bounded characteristic classes of foliated bundles in terms of the non-descendible quasi-morphisms on the universal covering of the structure group. As its application, we study the boundedness of…

Symplectic Geometry · Mathematics 2022-03-16 Morimichi Kawasaki , Shuhei Maruyama

A deflatable permutation class is one in which the simple permutations are contained in a proper subclass. Deflatable permutation classes are often easier to describe and enumerate than non-deflatable ones. Some theorems which guarantee…

Combinatorics · Mathematics 2014-09-19 M. H. Albert , M. D. Atkinson , Cheyne Homberger , Jay Pantone

Let $\Gamma$ be a finite group acting linearly on a vector space $V$. We compute the Lie algebra cohomology of the Lie algebra of $\Gamma$-invariant formal vector fields on $V$. We use this computation to define characteristic classes for…

Representation Theory · Mathematics 2007-05-23 Ilya Shapiro , Xiang Tang

We consider a proper flat fibration with real base and complex fibers. First we construct odd characteristic classes for such fibrations by a method that generalizes constructions of Bismut-Lott. Then we consider the direct image of a…

Differential Geometry · Mathematics 2017-02-16 Yeping Zhang

A holomorphic foliation $\mathscr{F}$ on a compact complex manifold $M$ is said to be an $\mathscr{L}$-foliation if there exists an action of a complex Lie group $G$ such that the generic leaf of $\mathscr{F}$ coincides with the generic…

Dynamical Systems · Mathematics 2007-05-23 Julie Deserti , Dominique Cerveau

We study those real $\mathcal{C}^\infty$ foliations in complex surfaces whose leaves are holomorphic curves. The main motivation is to try and understand these foliations in neighborhoods of curves: can we expect the space of foliations in…

Complex Variables · Mathematics 2021-05-12 Olivier Thom

We give a Kodaira-type classification of general singular fibers of a holomorphic Lagrangian fibration in Fujiki's class $\mathcal C$. Our approach is based on the study of the characteristic vector field of the discriminantal hypersurface,…

Algebraic Geometry · Mathematics 2007-10-15 Jun-Muk Hwang , Keiji Oguiso

This is a book on derived foliations, that are a generalisation of classical foliations in the context of derived geometry. The text starts with the basic definitions and constructions, then explore foliated cohomology (with crystal…

Algebraic Geometry · Mathematics 2025-07-31 Bertrand Toen , Gabriele Vezzosi

We study the question of when cyclic branched covers of knots admit taut foliations, have left-orderable fundamental group, and are not L-spaces.

Geometric Topology · Mathematics 2017-05-22 Cameron Gordon , Tye Lidman

A complete description of the deformation classes of real ruled manifolds is given. In particular, we prove that once the complex deformation class is fixed, the real deformation class is prescribed by the topology of the real structure.

Algebraic Geometry · Mathematics 2007-05-23 Jean-Yves Welschinger

We study holomorphic foliations with an affine homogeneous transverse structure. We give a friendly characterization of the case of transversely affine foliations in terms of matrix valued pairs of differential forms. This leads naturally…

Geometric Topology · Mathematics 2014-11-04 Bruno Scardua

The purpose of this paper is to present a ``Cech-De Rham'' model for the cohomology of leaf spaces. This model lends itself to the construction of characteristic classes (in the cohomology of classifying spaces) by explicit geometrical…

Differential Geometry · Mathematics 2007-05-23 Marius Crainic , Ieke Moerdijk

In this article, we show that for any deformation of analytic foliations, there exists a maximal analytic singular foliation on the space of parameters along the leaves of which the deformation is integrable.

Dynamical Systems · Mathematics 2016-10-20 Yohann Genzmer

We study left-invariant foliations $\mathcal{F}$ on Riemannian Lie groups $G$ generated by a subgroup $K$. We are interested in such foliations which are conformal and with minimal leaves of codimension two. We classify such foliations…

Differential Geometry · Mathematics 2020-10-28 Elsa Ghandour , Sigmundur Gudmundsson , Thomas Turner