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We prove a convexity theorem for the image of the moment map of a Hamiltonian torus action on a $b^m$-symplectic manifold.

Symplectic Geometry · Mathematics 2019-04-09 Victor Guillemin , Eva Miranda , Jonathan Weitsman

In this paper we prove a convexity and fibre-connectedness theorem for proper maps constructed by Thimm's trick on a connected Hamiltonian $G$-space $M$ that generate a Hamiltonian torus action on an open dense submanifold. Since these maps…

Symplectic Geometry · Mathematics 2021-10-06 Jeremy Lane

We investigate special lcs and twisted Hamiltonian torus actions on strict lcs manifolds and characterize them geometrically in terms of the minimal presentation. We prove a convexity theorem for the corresponding twisted moment map,…

Differential Geometry · Mathematics 2018-12-05 Florin Belgun , Oliver Goertsches , David Petrecca

We extend the famous convexity theorem of Atiyah, Guillemin and Sternberg to the case of non-Hamiltonian actions. We show that the image of a generalized momentum map is a bounded polytope times a vector space. We prove that this picture is…

Symplectic Geometry · Mathematics 2007-05-23 Andrea Giacobbe

We consider a Hamiltonian torus action on a compact connected symplectic manifold M. For a certain class of Lagrangian submanifolds Q of M we show that the image of Q under the momentum map is convex. As an application we complete the…

Symplectic Geometry · Mathematics 2007-05-23 Bernhard Kroetz , Michael Otto

The convexity theorem of Atiyah and Guillemin-Sternberg says that any connected compact manifold with Hamiltonian torus action has a moment map whose image is the convex hull of the image of the fixed point set. Sjamaar-Lerman proved that…

Differential Geometry · Mathematics 2007-05-23 Bong H. Lian , Bailin Song

In [GMPS] we proved that the moment map image of a $b$-symplectic toric manifold is a convex $b$-polytope. In this paper we obtain convexity results for the more general case of non-toric hamiltonian torus actions on $b$-symplectic…

Symplectic Geometry · Mathematics 2018-02-13 Victor Guillemin , Eva Miranda , Ana Rita Pires , Geoffrey Scott

In the early $1980$s a landmark result was obtained by Atiyah and independently Guillemin and Sternberg: the image of the momentum map for a torus action on a compact symplectic manifold is a convex polyhedron. Atiyah's proof makes use of…

Symplectic Geometry · Mathematics 2014-07-17 Kathleen Smith

In this paper, we consider generalized moment maps for Hamiltonian actions on $H$-twisted generalized complex manifolds introduced by Lin and Tolman \cite{Lin}. The main purpose of this paper is to show convexity and connectedness…

Differential Geometry · Mathematics 2009-01-06 Yasufumi Nitta

In this paper, we show the convexity of the image of a moment map on a transverse symplectic manifold equipped with a torus action under a certain condition. We also study properties of moment maps in the case of transverse K\"ahler…

Complex Variables · Mathematics 2015-09-15 Hiroaki Ishida

Let a torus T act effectively on a compact connected cooriented contact manifold, and let Psi be the natural momentum map on the symplectization. We prove that, if dim T > 2, the union of the origin with the image of Psi is a convex…

Symplectic Geometry · Mathematics 2014-10-01 River Chiang , Yael Karshon

Atiyah's formulation of what is nowadays called the convexity theorem of Atiyah-Guillemin-Sternberg has two parts: (a) the image of the moment map arising from a Hamiltonian action of a torus on a symplectic manifold is a convex polytope,…

Differential Geometry · Mathematics 2007-05-23 Augustin-Liviu Mare

We define a moment map associated to a smooth torus action on a smooth manifold, without a two-form. We define cobordisms of such structures, allowing non compact manifolds as long as the moment maps are proper. We prove that a compact…

dg-ga · Mathematics 2008-02-03 Yael Karshon

A generalized moment map is proposed for arbitrary symplectic actions of compact connected Lie groups on closed symplectic manifolds, in the spirit of the circle -valued maps introduced by D. McDuff in the case of non-Hamiltonian circle…

Symplectic Geometry · Mathematics 2016-09-07 Pierre Sleewaegen

Atiyah proved that the moment map image of the closure of an orbit of a complex torus action is convex. Brion generalized this result to actions of a complex reductive group. We extend their results to actions of a maximal solvable…

Symplectic Geometry · Mathematics 2010-11-02 Victor Guillemin , Reyer Sjamaar

Due to a previous result which states that contact varieties are isomorphic to certain varieties, the momentum polytopes of contact manifolds are convex.

Symplectic Geometry · Mathematics 2022-05-11 Amna Shaddad

We study generalized moment maps for a Hamiltonian action on a connected compact $H$-twisted generalized complex manifold introduced by Lin and Tolman and prove the convexity and connectedness properties of the generalized moment maps for a…

Differential Geometry · Mathematics 2007-10-23 Yasufumi Nitta

Let $(M,\omega)$ be a closed $2n$-dimensional symplectic manifold equipped with a Hamiltonian $T^{n-1}$-action. Then Atiyah-Guillemin-Sternberg convexity theorem implies that the image of the moment map is an $(n-1)$-dimensional convex…

Symplectic Geometry · Mathematics 2016-01-05 Yunhyung Cho , Min Kyu Kim

After observing that the well-known convexity theorems of symplectic geometry also hold for compact contact manifolds with an effective action of a torus whose Reeb vector field corresponds to an element of the Lie algebra of the torus, we…

Differential Geometry · Mathematics 2009-10-31 Charles P. Boyer , Krzysztof Galicki

Consider a Hamiltonian action of a compact connected Lie group on a conformal symplectic manifold. We prove a convexity theorem for the moment map under the assumption that the action is of Lee type, which establishes an analog of Kirwan's…

Symplectic Geometry · Mathematics 2023-11-27 Youming Chen , Reyer Sjamaar , Xiangdong Yang
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