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We prove that any symplectic resolution of the closure of a nilpotent orbit in a semi-simple complex Lie algebra is isomorphic to the collapsing of the cotangent bundle of a projective homogenous variety. Then we give a complete…

Algebraic Geometry · Mathematics 2015-06-26 Baohua Fu

Let $(M,\omega)$ be a Hamiltonian $G$-space with a momentum map $F:M \to {\frak g}^*$. It is well-known that if $\alpha$ is a regular value of $F$ and $G$ acts freely and properly on the level set $F^{-1}(G\cdot \alpha)$, then the reduced…

dg-ga · Mathematics 2008-02-03 L. Bates , E. Lerman

We consider various notions of completeness in symplectic topology and ask two related questions. Does a complete open symplectic manifold remain complete after excising a subset? Can two sets be made arbitrarily far apart by adjusting the…

Symplectic Geometry · Mathematics 2026-02-10 Yoel Groman

We answer a question of Oprea-Tralle on the realizability of symplectic algebras by symplectic manifolds in dimensions divisible by four, along with a question of Lupton-Oprea in all even dimensions. This will also allow us to address, in…

Algebraic Topology · Mathematics 2020-11-06 Aleksandar Milivojevic

A topological condition is given, characterizing which closed manifolds in dimensions < 8 (and conjecturally in general) admit symplectic structures. The condition is the existence of a certain fibration-like structure called a hyperpencil.…

Symplectic Geometry · Mathematics 2007-05-23 Robert E. Gompf

We investigate spaces of symplectic embeddings of $n\leq 4$ balls into the complex projective plane. We prove that they are homotopy equivalent to explicitly described algebraic subspaces of the configuration spaces of $n$ points. We…

Symplectic Geometry · Mathematics 2024-02-09 Sílvia Anjos , Jarek Kędra , Martin Pinsonnault

We show that a small neighborhood of a closed symplectic submanifold in a geometrically bounded aspherical symplectic manifold has non-vanishing symplectic homology. As a consequence, we establish the existence of contractible closed…

Differential Geometry · Mathematics 2007-05-23 Kai Cieliebak , Viktor L. Ginzburg , Ely Kerman

We study some topological properties of maximal ideal spaces of certain algebras of almost periodic functions. Our main result is that such spaces are contractible. We present certain corollaries of this result.

Functional Analysis · Mathematics 2007-05-23 A. Brudnyi

We present a handlebody construction of small symplectic caps, and hence of small closed symplectic 4-manifolds. We use this to construct handlebody descriptions of symplectic embeddings of rational homology balls in…

Geometric Topology · Mathematics 2025-08-21 John B. Etnyre , Hyunki Min , Lisa Piccirillo , Agniva Roy

The space ${\mathcal A}$ of almost complex structures on a closed manifold $M$ is studied. A natural parametrization of the space ${\mathcal A}$ is defined. It is shown, that ${\mathcal A}$ is a infinite dimensional complex weak…

Differential Geometry · Mathematics 2007-05-23 N. A. Daurtseva , N. K. Smolentsev

In this paper we compute the homotopy groups of the symplectomorphism groups of the 3-, 4- and 5-point blow-ups of the projective plane (considered as monotone symplectic Del Pezzo surfaces). Along the way, we need to compute the homotopy…

Symplectic Geometry · Mathematics 2014-05-13 Jonathan David Evans

This paper studies the question of when a loop $\phi$ in the group Symp$(M,\omega)$ of symplectomorphisms of a symplectic manifold $(M,\omega)$ is isotopic to a loop that is generated by a time-dependent Hamiltonian function. (Loops with…

dg-ga · Mathematics 2007-05-23 François Lalonde , Dusa McDuff , Leonid Polterovich

We show that every orientable infinite-type surface is properly rigid as a consequence of a more general result. Namely, we prove that if a homotopy equivalence between any two non-compact orientable surfaces is a proper map, then it is…

Geometric Topology · Mathematics 2024-12-25 Sumanta Das

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

Let (M,\omega) be a symplectic manifold, and Sigma a compact Riemann surface. We define a 2-form on the space of immersed symplectic surfaces in M, and show that the form is closed and non-degenerate, up to reparametrizations. Then we give…

Symplectic Geometry · Mathematics 2011-08-02 Joseph Coffey , Liat Kessler , Alvaro Pelayo

We obtain structure results for locally conformally symplectic Lie algebras. We classify locally conformally symplectic structures on four-dimensional Lie algebras and construct locally conformally symplectic structures on compact quotients…

Differential Geometry · Mathematics 2023-06-13 Daniele Angella , Giovanni Bazzoni , Maurizio Parton

A topological space $A$ is said to be compatible with a set $\Sigma$ of equations (involving operation symbols $F_t$) iff there are continuous operations $\overline F_t$ identically satisfying $\Sigma$ on $A$. The paper's main focus is on…

Rings and Algebras · Mathematics 2014-02-18 Walter Taylor

This article investigates the complex symplectic geometry of the deformation space of complex projective structures on a closed oriented surface of genus at least 2. The cotangent symplectic structure given by the Schwarzian parametrization…

Differential Geometry · Mathematics 2015-06-03 Brice Loustau

In this paper, we prove homological stability of symplectomorphisms and extended hamiltonians of surfaces made discrete. We construct an isomorphism from the stable homology group of symplectomorphisms and extended Hamiltonians of surfaces…

Algebraic Topology · Mathematics 2018-03-06 Sam Nariman

In this note we prove that a positive multiple of each even-dimensional integral homology class of a compact symplectic manifold $(M^{2n}, \omega)$ can be represented as the difference of the fundamental classes of two symplectic…

Symplectic Geometry · Mathematics 2014-07-15 Hong-Van Le