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A C-symplectic structure is a complex-valued 2-form which is holomorphically symplectic for an appropriate complex structure. We prove an analogue of Moser's isotopy theorem for families of C-symplectic structures and list several…

Algebraic Geometry · Mathematics 2025-08-26 Andrey Soldatenkov , Misha Verbitsky

A threefold extremal transition $Y \searrow X$ consists of a crepant extremal contraction $\phi \colon Y \to \bar Y$ with curve class $\ell \in \operatorname{NE}(Y)$, followed by a smoothing $\bar Y\rightsquigarrow X$. We consider the Type…

Algebraic Geometry · Mathematics 2025-12-01 Shuang-Yen Lee , Chin-Lung Wang , Sz-Sheng Wang

This paper is concerned with non-symplectic involutions of irreducible symplectic manifolds of $K3^{[n]}$-type. We will give a criterion for deformation equivalence and use this to give a lattice-theoretic description of all deformation…

Algebraic Geometry · Mathematics 2016-07-19 Malek Joumaah

We prove abundance for a minimal Kaehler threefold which is not both simple and non-Kummer. Recall that a variety is simple if there is no compact subvariety of positive dimension through a sufficiently general point . Furthermore we prove…

Algebraic Geometry · Mathematics 2009-09-25 Thomas Peternell

We generalize the Hodge version of the global Torelli theorem in the framework of irreducible symplectic orbifolds. We also propose a generalization of several results related to the K\"ahler cone and the notion of wall divisors introduced…

Algebraic Geometry · Mathematics 2025-05-27 Grégoire Menet , Ulrike Rieß

We introduce a symplectic surgery in six dimensions which collapses Lagrangian three-spheres and replaces them by symplectic two-spheres. Under mirror symmetry it corresponds to an operation on complex 3-folds studied by Clemens, Friedman…

Symplectic Geometry · Mathematics 2007-05-23 I. Smith , R. P. Thomas , S. -T. Yau

The paper associates Lagrangian submanifolds in symplectic toric varieties to certain tropical curves inside the convex polyhedral domains of $\R^n$ that appear as the images of the moment map of the toric varieties. We pay a particular…

Symplectic Geometry · Mathematics 2019-01-29 Grigory Mikhalkin

This paper deals with symplectic varieties which do not have symplectic resolutions. Some moduli spaces of semi-stable torsion-free sheaves on a K3 surface, and symplectic V-manifolds are such varieties. We shall prove local Torelli theorem…

Algebraic Geometry · Mathematics 2016-09-07 Yoshinori Namikawa

We prove an important partial case of the pseudo-Riemannian version of the projective Lichnerowicz conjecture stating that a complete manifold admitting an essential group of projective transformations is the round sphere (up to a finite…

Differential Geometry · Mathematics 2015-05-13 Volodymyr Kiosak , Vladimir S. Matveev

This article discusses the recent transcendental techniques used in the proofs of the following three conjectures. (1)~The plurigenera of a compact projective algebraic manifold are invariant under holomorphic deformation. (2)~There exists…

Complex Variables · Mathematics 2007-05-23 Yum-Tong Siu

In this paper, we extend the Atiyah--Guillemin--Sternberg convexity theorem and Delzant's classification of symplectic toric manifolds to presymplectic manifolds. We also define and study the Morita equivalence of presymplectic toric…

Symplectic Geometry · Mathematics 2017-06-01 Tudor Ratiu , Nguyen Tien Zung

For a Lagrangian torus A in a simply-connected projective symplectic manifold M, we prove that M has a hypersurface disjoint from a deformation of A. This implies that a Lagrangian torus in a compact hyperk\"ahler manifold is a fiber of an…

Algebraic Geometry · Mathematics 2015-06-03 Jun-Muk Hwang , Richard M. Weiss

For a stratified symplectic space, a suitable concept of stratified Kaehler polarization, defined in terms of an appropriate Lie-Rinehart algebra, encapsulates Kaehler polarizations on the strata and the behaviour of the polarizations…

Differential Geometry · Mathematics 2007-05-23 Johannes Huebschmann

A $K3$ surface with an ample divisor of self-intersection 2 is a double cover of the plane branched over a sextic curve. We conjecture that a similar statement holds for the generic couple $(X,H)$ with $X$ a deformation of $(K3)^{[n]}$ and…

Algebraic Geometry · Mathematics 2007-05-23 Kieran G. O'Grady

We set up a topological framework for degenerations of symplectic manifolds into singular spaces paying a special attention to the behavior of Lagrangian manifolds and their (holomorphic) membranes. We show that degenerations into singular…

Symplectic Geometry · Mathematics 2023-03-14 Sergey Galkin , Grigory Mikhalkin

We construct projectors in the ring of correspondences of a complex uniruled 3-fold $X$ which lift the Kuenneth components of the diagonal in singular cohomology and have other properties which were conjectured by J. Murre. Such Murre…

alg-geom · Mathematics 2014-10-24 Pedro Luis del Angel , Stefan Müller-Stach

An important question with a rich history is the extent to which the symplectic category is larger than the Kaehler category. Many interesting examples of non-Kaehler symplectic manifolds have been constructed. However, sufficiently large…

dg-ga · Mathematics 2008-02-03 Susan Tolman

We construct monotone Lagrangian tori in the standard symplectic vector space, in the complex projective space and in products of spheres. We explain how to classify these Lagrangian tori up to symplectomorphism and Hamiltonian isotopy, and…

Symplectic Geometry · Mathematics 2010-04-01 Yuri Chekanov , Felix Schlenk

Almost toric manifolds form a class of singular Lagrangian fibered symplectic manifolds that is a natural generalization of toric manifolds. Notable examples include the K3 surface, the phase space of the spherical pendulum and rational…

Symplectic Geometry · Mathematics 2007-05-23 Naichung Conan Leung , Margaret Symington

In the case of toric varieties, we continue the pursuit of Kontsevich's fundamental insight, Homological Mirror Symmetry, by unifying it with the Mori program. We give a refined conjectural version of Homological Mirror Symmetry relating…

Algebraic Geometry · Mathematics 2013-02-05 Matthew Ballard , Colin Diemer , David Favero , Ludmil Katzarkov , Gabriel Kerr