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In this paper we extend the results of Kirwan et alii on convexity properties of the moment map for Hamiltonian group actions, and on the connectedness of the fibers of the moment map, to the case of non-compact orbifolds. Our motivation is…

dg-ga · Mathematics 2016-08-31 Eugene Lerman , Eckhard Meinrenken , Sue Tolman , Chris Woodward

We introduce the notion of a point on a locally closed subset of a symplectic manifold being "locally rigid" with respect to that subset, prove that this notion is invariant under symplectic homeomorphisms, and show that coisotropic…

Symplectic Geometry · Mathematics 2023-03-01 Michael Usher

Let M be a compact oriented even-dimensional manifold. This note constructs a compact symplectic manifold S of the same dimension and a map f from S to M of strictly positive degree. The construction relies on two deep results: the first is…

Symplectic Geometry · Mathematics 2020-08-19 Joel Fine , Dmitri Panov

We prove one deformation theoretic extension of the Gromov non-squeezing phenomenon to $lcs$ structures, or locally conformally symplectic structures, which suitably generalize both symplectic and contact structures. We also conjecture an…

Symplectic Geometry · Mathematics 2023-09-19 Yasha Savelyev

We give a generalization of toric symplectic geometry to Poisson manifolds which are symplectic away from a collection of hypersurfaces forming a normal crossing configuration. We introduce the tropical momentum map, which takes values in a…

Symplectic Geometry · Mathematics 2017-03-13 Marco Gualtieri , Songhao Li , Alvaro Pelayo , Tudor Ratiu

We consider two natural Lagrangian intersection problems in the context of symplectic toric manifolds: displaceability of torus orbits and of a torus orbit with the real part of the toric manifold. Our remarks address the fact that one can…

Symplectic Geometry · Mathematics 2012-01-18 Miguel Abreu , Leonardo Macarini

In this paper we show that the transverse image of the momentum map of a Hamiltonian Lie group action admits a natural integral affine stratification with the property that over each stratum the momentum map is an equivariantly locally…

Symplectic Geometry · Mathematics 2025-09-01 Maarten Mol

We introduce the notion of a weak (homotopy) moment map associated to a Lie group action on a multisymplectic manifold. We show that the existence/uniqueness theory governing these maps is a direct generalization from symplectic geometry.…

Symplectic Geometry · Mathematics 2018-07-05 Jonathan Herman

The Local-to-Global-Principle used in the proof of convexity theorems for momentum maps has been extracted as a statement of pure topology enriched with a structure of convexity. We extend this principle to not necessarily closed maps…

Symplectic Geometry · Mathematics 2012-02-14 Wolfgang Rump , Jenny Santoso

As noted long ago by Atiyah and Bott, the classical Yang-Mills action on a Riemann surface admits a beautiful symplectic interpretation as the norm-square of a moment map associated to the Hamiltonian action by gauge transformations on the…

High Energy Physics - Theory · Physics 2010-12-23 Chris Beasley

We study piecewise linear knot diagrams in the base of almost toric fibrations of symplectic four-manifolds. These diagrams translate to deformations of the almost toric fibration. We give several applications to symplectic topology, among…

Symplectic Geometry · Mathematics 2025-11-07 Joel Schmitz

The moment map $\mu$ is a central concept in the study of Hamiltonian actions of compact Lie groups $K$ on symplectic manifolds. In this short note, we propose a theory of moment maps coupled with an $\mathrm{Ad}_K$-invariant convex…

Differential Geometry · Mathematics 2022-08-09 King Leung Lee , Jacob Sturm , Xiaowei Wang

Let L->M be a Hermitian line bundle over a compact manifold. Write S for the space of all unitary connections in L whose curvatures define symplectic forms on M and G for the group of unitary bundle isometries of L, which acts on S by…

Symplectic Geometry · Mathematics 2017-03-24 Joel Fine

We establish a Hard Lefschetz Theorem for the de Rham cohomology of compact Vaisman manifolds. A similar result is proved for the basic cohomology with respect to the Lee vector field. Motivated by these results, we introduce the notions of…

Differential Geometry · Mathematics 2018-11-21 Beniamino Cappelletti-Montano , Antonio De Nicola , Juan Carlos Marrero , Ivan Yudin

In this paper we generalize to coisotropic actions of compact Lie groups a theorem of Guillemin on deformations of Hamiltonian structures on compact symplectic manifolds. We show how one can reconstruct from the moment polytope the…

Symplectic Geometry · Mathematics 2008-10-01 Lucio Bedulli , Anna Gori

A natural way of generalising Hamiltonian toric manifolds is to permit the presence of generic isolated singularities for the moment map. For a class of such ``almost-toric 4-manifolds'' which admits a Hamiltonian $S^1$-action we show that…

Symplectic Geometry · Mathematics 2007-05-23 San Vu Ngoc

Let $G_{\P}$ be a compact simple Poisson-Lie group equipped with a Poisson structure $\P$ and $(M, \o)$ be a symplectic manifold. Assume that $M$ carries a Poisson action of $G_{\P}$ and there is an equivariant moment map in the sense of Lu…

dg-ga · Mathematics 2008-02-03 Anton Yu. Alekseev

Given two locally conformal symplectic (LCS) structures on manifolds $M_1$ and $M_2$, we construct a natural $\R^+$-torsor of locally conformal symplectic structures on a certain covering space $M_1 \boxplus M_2$ of $M_1 \times M_2$. As the…

Symplectic Geometry · Mathematics 2024-01-29 Baptiste Chantraine , Kevin Sackel

Let $G$ be a compact connected semisimple Lie group. We extend the techniques of Weinstein [W] to give a construction in group cohomology of symplectic forms $\omega$ on \lq twisted' moduli spaces of representations of the fundamental group…

alg-geom · Mathematics 2008-02-03 Lisa C. Jeffrey

We prove a normal form theorem for principal Hamiltonian actions on Poisson manifolds around the zero locus of the moment map. The local model is the generalization to Poisson geometry of the classical minimal coupling construction from…

Symplectic Geometry · Mathematics 2023-02-07 Pedro Frejlich , Ioan Marcut