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Let G be a torus of dimension n > 1 and M a compact Hamiltonian G-manifold with $M^G$ finite. A circle, $S^1$, in G is generic if $M^G = M^{S^1}$. For such a circle the moment map associated with its action on M is a perfect Morse function.…

Symplectic Geometry · Mathematics 2007-05-23 Victor Guillemin , Catalin Zara

We give positive formulas for the restriction of a Schubert Class to a T-fixed point in the equivariant K-theory and equivariant cohomology of the Lagrangian Grassmannian. Our formulas rely on a result of Ghorpade-Raghavan, which gives an…

Algebraic Geometry · Mathematics 2007-05-23 V. Kreiman

Let $G/P$ be a generalized flag variety, where $G$ is a complex semisimple connected Lie group and $P\subset G$ a parabolic subgroup. Let also $X\subset G/P$ be a Schubert variety. We consider the canonical embedding of $X$ into a…

Symplectic Geometry · Mathematics 2009-05-28 Augustin-Liviu Mare

We study the torus-equivariant homology $H_*^T(\mathrm{Gr}_G)$ of the affine Grassmannian $\mathrm{Gr}_G$, where $G=\mathrm{Sp}_{2n}(\mathbb{C})$ is the symplectic group. This homology admits a natural ring structure and a Schubert basis,…

Representation Theory · Mathematics 2025-11-27 Takeshi Ikeda , Shinsuke Iwao , Mark Shimozono

Characteristic classes of Schubert varieties can be used to study the geometry and the combinatorics of homogeneous spaces. We prove a relation between elliptic classes of Schubert varieties on a generalized full flag variety and those on…

Algebraic Geometry · Mathematics 2021-01-01 Richard Rimanyi , Andrzej Weber

Given a closed, oriented surface, possibly with boundary, and a mapping class, we obtain sharp lower bounds on the number of fixed points of a surface symplectomorphism (i.e. area-preserving map) in the given mapping class, both with and…

Symplectic Geometry · Mathematics 2023-08-02 Andrew Cotton-Clay

Let $(M, \omega)$ be a connected, compact symplectic manifold equipped with a Hamiltonian $G$ action, where $G$ is a connected compact Lie group. Let $\phi$ be the moment map. In \cite{L}, we proved the following result for $G=S^1$ action:…

Symplectic Geometry · Mathematics 2011-11-09 Hui Li

A driving question in (quantum) cohomology of flag varieties is to find non-recursive, positive combinatorial formulas for expressing the product of two classes in a particularly nice basis, called the Schubert basis. Bertram,…

Algebraic Geometry · Mathematics 2020-08-11 Anna Bertiger , Elizabeth Milićević , Kaisa Taipale

We consider compact K\"ahler manifolds acted on by a connected compact Lie group $K$ of isometries in Hamiltonian fashion. We prove that the squared moment map $\|\mu\|^2$ is constant if and only if the manifold is biholomorphically and…

Symplectic Geometry · Mathematics 2007-05-23 Anna Gori , Fabio Podesta'

We give the formula for multiplying a Schubert class on an odd orthogonal or symplectic flag manifold by a special Schubert class pulled back from a Grassmannian of maximal isotropic subspaces. This is also the formula for multiplying a…

Combinatorics · Mathematics 2016-11-08 Nantel Bergeron , Frank Sottile

Let M be a compact Kahler manifold equipped with a Hamiltonian action of a compact Lie group G. In this paper, we study the geometric quantization of the symplectic quotient M//G. Guillemin and Sternberg [Invent. Math. 67 (1982), 515--538]…

Symplectic Geometry · Mathematics 2012-10-19 Brian C. Hall , William D. Kirwin

We consider compact symplectic manifolds acted on effectively by a compact connected Lie group $K$ in a Hamiltonian fashion. We prove that the squared moment map $||\mu||^2$ is constant if and only if $K$ is semisimple and the manifold is…

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

We develop the basic theory of Maurer-Cartan simplicial sets associated to (shifted complete) $L_\infty$ algebras equipped with the action of a finite group. Our main result asserts that the inclusion of the fixed points of this equivariant…

Algebraic Topology · Mathematics 2022-12-14 José M. Moreno-Fernández , Felix Wierstra

We show that generic symplectic quotients of a Hamiltonian $G$-space $M$ by the action of a compact connected Lie group $G$ are also symplectic quotients of the same manifold $M$ by a compact torus. The torus action in question arises from…

Symplectic Geometry · Mathematics 2025-01-01 Peter Crooks , Jonathan Weitsman

The main goal of this paper is to extend two fundamental combinatorial results in Schubert calculus on flag manifolds from equivariant cohomology and $K$-theory to equivariant elliptic cohomology. The foundations of elliptic Schubert…

Combinatorics · Mathematics 2025-10-07 Cristian Lenart , Rui Xiong , Changlong Zhong

On conformally compact manifolds of arbitrary signature, we use conformal geometry to identify a natural (and very general) class of canonical boundary problems. It turns out that these encompass and extend aspects of already known…

Differential Geometry · Mathematics 2015-11-05 A. Rod Gover , Andrew Waldron

A key result in equivariant symplectic geometry is Delzant's classification of compact connected symplectic toric manifolds. The moment map induces an embedding of the quotient of the manifold by the torus action into the dual of the Lie…

Symplectic Geometry · Mathematics 2015-07-23 Yael Karshon , Eugene Lerman

Let $X$ be a projective variety with a torus action, which for simplicity we assume to have dimension 1. If $X$ is a smooth complex variety, then the geometric invariant theory quotient $X//G$ can be identifed with the symplectic reduction…

alg-geom · Mathematics 2008-02-03 Dan Edidin , William Graham

Let G be a compact connected Lie group and H, the centralizer of a one-parameter subgroup in G. Combining the ideas of Bott-Samelson resulotions of Schubert varieties and the enumerative formula on a twisted products of 2-spheres obatained…

Algebraic Geometry · Mathematics 2014-04-02 Haibao Duan

We sketch the proof of a connection between the canonical (0-)dimension of semisimple split simply connected groups and cohomology of their full flag varieties. Using this connection, we get a new estimate of the canonical (0-)dimension of…

Algebraic Geometry · Mathematics 2025-03-06 Rostislav Devyatov