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We use Hamiltonian Floer theory to recover and generalize a classic rigidity theorem of Ekelend and Lasry. That theorem can be rephrased as an assertion about the existence of multiple closed Reeb orbits for certain tight contact forms on…

Symplectic Geometry · Mathematics 2019-02-20 Ely Kerman

We characterize the rigidity of Carnot groups in the class of $C^2$ contact maps in terms of complex characteristics. Furthermore, we obtain a Liouville type theorem for Carnot groups which states that 1-quasiconformal maps form finite…

Differential Geometry · Mathematics 2010-07-09 A. Ottazzi , B. Warhurst

We prove that various classical conformal diffeomorphism groups, which are known to be essential [1], are in fact properly essential. This is a consequence of a local criterion on a conformal diffeomorphism in the form of a cohomological…

Symplectic Geometry · Mathematics 2011-08-01 Stefan Müller , Peter Spaeth

We give simple characterizations of contact 1-forms in terms of Dirac structures. We also relate normal almost contact structures to the theory of Dirac structures.

Differential Geometry · Mathematics 2016-08-16 David Iglesias-Ponte , Aïssa Wade

Precontact manifolds extend contact geometry by weakening the maximal non-integrability condition of the defining $1$-form. We clarify the geometric foundations of this structure by studying general pairs of a $1$-form and a $2$-form under…

Differential Geometry · Mathematics 2026-02-05 Xavier Gràcia , Àngel Martínez-Muñoz , Xavier Rivas

We prove an analogue of E. Levi's Continuity Principle for meromorphic mappings with values in arbitrary compact complex manifolds in place of the Riemann sphere $\cc\pp^1$. The result is achieved by introducing a new extension method for…

Complex Variables · Mathematics 2009-09-25 Sergey Ivashkovich

In this paper, we study normal complex contact metric manifolds and we get some general results on them. Moreover, we obtained the general expression of the curvature tensor field for arbitrary vector fields. Furthermore, we show that the…

Differential Geometry · Mathematics 2015-10-21 Aysel Turgut Vanli , Inan Unal

We study constructions of contact forms on closed manifolds. A notion of strong symplectic fold structure is defined and we prove that there is a contact form on $M \x X$ provided that $M$ admits such a structure and $X$ is contact. This…

Symplectic Geometry · Mathematics 2013-08-13 Bogusław Hajduk , Rafał Walczak

This paper begins the study of relations between Riemannian geometry and global properties of contact structures on 3-manifolds. In particular we prove an analog of the sphere theorem from Riemannian geometry in the setting of contact…

Symplectic Geometry · Mathematics 2015-09-14 John B. Etnyre , Rafal Komendarczyk , Patrick Massot

We show that complex symplectic structures need not be preserved under small deformations, and we find sufficient conditions for this to happen. We study various cohomologies of compact complex symplectic manifolds, obtaining some…

Differential Geometry · Mathematics 2025-07-08 Giovanni Bazzoni , Marco Freibert , Adela Latorre , Nicoletta Tardini

We study the formality of orientable sphere bundles over connected compact manifolds. When the base manifold is formal, we prove that the formality of the bundle is equivalent to the vanishing of the Bianchi-Massey tensor introduced by…

Algebraic Topology · Mathematics 2025-08-20 Jiawei Zhou

This note describes some recent results about the homotopy properties of Hamiltonian loops in various manifolds, including toric manifolds and one point blow ups. We describe conditions under which a circle action does not contract in the…

Symplectic Geometry · Mathematics 2009-01-18 Dusa McDuff

In this paper we are interested in characterizing the standard contact sphere in terms of dynamically convex contact manifolds which admit a Liouville filling with vanishing symplectic homology. We first observe that if the filling is…

Symplectic Geometry · Mathematics 2024-04-05 Myeonggi Kwon , Takahiro Oba

In the present paper, we establish a general Kawamata-Viehweg-Koll\'ar-Nadel type vanishing theorem for higher direct images in terms of numerical dimension for closed positive currents on compact K\"ahler manifolds, unifying a number of…

Complex Variables · Mathematics 2026-02-17 Xiankui Meng , Chenghao Qing , Xiangyu Zhou

We collect our recent results ([5] and [8]) and we get the equivalence of the three notions of the title under some conditions. We then use this equivalence in order to prove some consequences about Sasakian manifolds, complex almost…

dg-ga · Mathematics 2019-01-08 A. Moroianu , U. Semmelmann

New estimates are derived concerning the behavior of self-dual hamonic 2-forms on a compact Riemannian 4-manifold with non-trivial Seiberg-Witten invariants. Applications include a vanishing theorem for certain Seiberg-Witten invariants on…

Differential Geometry · Mathematics 2007-05-23 Claude LeBrun

In the spirit of Sullivan's paper "Cycles for the Dynamical Study of Foliated Manifolds and Complex Manifolds", existence of a contact structure on a closed manifold $M$ is shown to be equivalent to existence of an ample $S^1$-invariant…

Differential Geometry · Mathematics 2015-12-14 Mélanie Bertelson , Cédric De Groote

In this paper, by using monotonicity formulas for vector bundle-valued $p$-forms satisfying the conservation law, we first obtain general $L^2$ global rigidity theorems for locally conformally flat (LCF) manifolds with constant scalar…

Differential Geometry · Mathematics 2016-04-19 Yuxin Dong , Hezi Lin , Shihshu Walter Wei

A contact hypersurface in a Kaehler manifold is a real hypersurface for which the induced almost contact metric structure determines a contact structure. We carry out a systematic study of contact hypersurfaces in Kaehler manifolds. We then…

Differential Geometry · Mathematics 2013-12-11 Jurgen Berndt , Young Jin Suh

We prove the following theorem for Holomorphic Foliations in compact complex kaehler manifolds: if there is a compact leaf with finite holonomy, then every leaf is compact with finite holonomy. As corollary we reobtain stability theorems…

Geometric Topology · Mathematics 2010-04-20 Jorge Vitorio Pereira
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