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For a compact complex manifold, we introduce holomorphic foliations associated with certain abelian subgroups of the automorphism group. Such foliations are generalizations of holomorphic principal torus bundles. If there exists a…

Complex Variables · Mathematics 2018-01-22 Hiroaki Ishida , Hisashi Kasuya

We study generalized complex cohomologies of generalized complex structures constructed from certain symplectic fibre bundles over complex manifolds. We apply our results in the case of left-invariant generalized complex structures on…

Differential Geometry · Mathematics 2017-12-12 Daniele Angella , Simone Calamai , Hisashi Kasuya

We construct a natural generalized complex structure on the total space of any bundle endowed with a Chern connection and whose typical fibre is a homogeneous symplectic manifold. This extends known constructions of generalized complex…

Differential Geometry · Mathematics 2013-04-09 Radu Pantilie

We show that, under a certain condition, contact 5-manifolds can `coarsely' distinguish smooth structures on compact Stein 4-manifolds via contact open books. We also give a simple sufficient condition for an infinite family of Stein…

Geometric Topology · Mathematics 2016-04-13 Kouichi Yasui

We discuss conditions for the integrability of an almost complex structure defined on the total space of an induced Hopf S^3-bundle over a Sasakian manifold . As an application, we obtain an uncountable family of inequivalent complex…

Differential Geometry · Mathematics 2007-05-23 Liviu Ornea , Paolo Piccinni

Manifolds all of whose geodesics are closed have been studied a lot, but there are only few examples known. The situation is different if one allows in addition for orbifold singularities. We show, nevertheless, that the abundance of new…

Differential Geometry · Mathematics 2018-11-27 Manual Amann , Christian Lange , Marco Radeschi

We construct a simple topological invariant of certain 3-manifolds, including quotients of the 3-sphere by finite groups, based on the fact that the tangent bundle of an orientable 3-manifold is trivialisable. This invariant is strong…

Geometric Topology · Mathematics 2007-05-23 Siddhartha Gadgil

We discuss our recent results on the existence and classification problem of complex and Kaehler structures on compact solvmanifolds. In particular, we determine in this paper all the complex surfaces which are diffeomorphic to compact…

Complex Variables · Mathematics 2008-04-30 Keizo Hasegawa

We characterize the oriented Seifert-fibered three-manifolds which admit positive, transverse contact structures.

Symplectic Geometry · Mathematics 2014-10-01 Paolo Lisca , Gordana Matic

This is a summary of some of the basic facts about flat 2-orbifold groups, otherwise known as 2-dimensional crystallographic groups. We relate the geometric and topological presentations of these groups, and consider structures…

Group Theory · Mathematics 2017-08-15 J. A. Hillman

We study type one generalized complex and generalized Calabi--Yau manifolds. We introduce a cohomology class that obstructs the existence of a globally defined, closed 2-form which agrees with the symplectic form on the leaves of the…

Differential Geometry · Mathematics 2023-05-26 Michael Bailey , Gil R. Cavalcanti , Marco Gualtieri

We analyze from a general perspective all possible supersymmetric generalizations of symplectic and metric structures on smooth manifolds. There are two different types of structures according to the even/odd character of the corresponding…

High Energy Physics - Theory · Physics 2008-05-16 M. Asorey , P. M. Lavrov

Singular fibrations generalize achiral Lefschetz fibrations of 4-manifolds over surfaces while sharing some of their properties. For instance, relatively minimal singular fibrations are determined by their monodromy. We explain how to…

Geometric Topology · Mathematics 2024-04-24 Louis Funar

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 construct a compact example of 7- dimensional manifold endowed with a weakly integrable generalized G_2-structure with respect to a closed and non trivial 3-form. Moreover, we investigate which type of SU(3)-structures on a 6-dimensional…

Differential Geometry · Mathematics 2007-11-24 Anna Fino , Adriano Tomassini

This paper is dedicated to the study of deformations of coassociative 4-folds in a G_2 manifold which have conical singularities. We stratify the types of deformations allowed into three problems. The main result for each problem states…

Differential Geometry · Mathematics 2008-05-20 Jason Lotay

Brunella's classification implies that every smooth foliation on a compact complex surface admits a singular transversely projective structure. However, Biswas and Dumitrescu's recent work shows that certain foliations on compact complex…

Complex Variables · Mathematics 2025-07-08 Gabriel Fazoli , Caio Melo , Jorge Vitório Pereira

In this paper we prove that the closed $4$-ball admits non-K\"ahler complex structures with strictly pseudoconcave boundary. Moreover, the induced contact structure on the boundary $3$-sphere is overtwisted.

Complex Variables · Mathematics 2023-08-02 Naohiko Kasuya , Daniele Zuddas

In this paper we characterize smooth complex projective varieties that admit a quadric bundle structure on some dense open subset in terms of the geometry of certain families of rational curves.

Algebraic Geometry · Mathematics 2008-11-07 Carolina Araujo

Given some type of fibration on a 4-manifold $X$ with a torus regular fiber $T$, we may produce a new 4-manifold $X_T$ by performing torus surgery on $T$. There is a natural way to extend the fibration to $X_T$, but a multiple fiber…

Geometric Topology · Mathematics 2015-02-25 Kyle Larson