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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 construct the Schubert basis of the torus-equivariant K-homology of the affine Grassmannian of a simple algebraic group G, using the K-theoretic NilHecke ring of Kostant and Kumar. This is the K-theoretic analogue of a construction of…

Combinatorics · Mathematics 2019-02-20 Thomas Lam , Anne Schilling , Mark Shimozono

We investigate algebraicity properties of quotients of complex spaces by complex reductive Lie groups G. We obtain a projectivity result for compact momentum map quotients of algebraic G-varieties. Furthermore, we prove equivariant versions…

Algebraic Geometry · Mathematics 2011-04-13 Daniel Greb

We introduce the most general to date version of the permutation-equivariant quantum K-theory, and express its total descendant potential in terms of cohomological Gromov-Witten invariants. This is the higher-genus analogue of adelic…

Algebraic Geometry · Mathematics 2017-09-12 Alexander Givental

We prove the conjectures of Graham-Kumar and Griffeth-Ram concerning the alternation of signs in the structure constants for torus-equivariant K-theory of generalized flag varieties G/P. These results are immediate consequences of an…

Algebraic Geometry · Mathematics 2017-03-14 Dave Anderson , Stephen Griffeth , Ezra Miller

We study the ergodic properties of eigenfunctions of Schr\"odinger operators on a closed connected Riemannian manifold $M$ in case that the underlying Hamiltonian system possesses certain symmetries. More precisely, let $M$ carry an…

Mathematical Physics · Physics 2016-02-15 Benjamin Küster , Pablo Ramacher

In this paper we study a natural decomposition of $G$-equivariant $K$-theory of a proper $G$-space, when $G$ is a Lie group with a compact normal subgroup $A$ acting trivially. Our decomposition could be understood as a generalization of…

Algebraic Topology · Mathematics 2024-09-10 Andrés Angel , Edward Becerra , Mario Velásquez

This paper gives a partial desingularisation construction for hyperk\"ahler quotients and a criterion for the surjectivity of an analogue of the Kirwan map to the cohomology of hyperk\"ahler quotients. This criterion is applied to some…

Symplectic Geometry · Mathematics 2009-06-22 Lisa Jeffrey , Young-Hoon Kiem , Frances Kirwan

We prove an analogue of Kirwan surjectivity in the setting of equivariant basic cohomology of K-contact manifolds. If the Reeb vector field induces a free $S^1$-action, the $S^1$-quotient is a symplectic manifold and our result reproduces…

Differential Geometry · Mathematics 2018-03-13 Lana Casselmann

We apply results of Harada, Holm and Henriques to prove that the Atiyah-Segal equivariant complex $K$-theory ring of a divisive weighted projective space (which is singular for nontrivial weights) is isomorphic to the ring of integral…

Algebraic Topology · Mathematics 2015-02-10 Megumi Harada , Tara S. Holm , Nigel Ray , Gareth Williams

Consider a Hamiltonian action of a compact connected Lie group on a symplectic manifold $(M,\omega)$. Conjecturally, under suitable assumptions there exists a morphism of cohomological field theories from the equivariant Gromov-Witten…

Symplectic Geometry · Mathematics 2012-09-28 Fabian Ziltener

We give a general formula for the equivariant complex $K$-theory $K_G^*(V)$ of a finite dimensional real linear space $V$ equipped with a linear action of a compact group $G$ in terms of the representation theory of a certain double cover…

K-Theory and Homology · Mathematics 2009-03-06 Siegfried Echterhoff , Oliver Pfante

This is the third paper of a series relating the equivariant twisted $K$-theory of a compact Lie group $G$ to the ``Verlinde space'' of isomorphism classes of projective lowest-weight representations of the loop groups. Here, we treat…

Algebraic Topology · Mathematics 2007-05-23 Daniel S. Freed , Michael J. Hopkins , Constantin Teleman

In the present paper, we discuss applications of the derived completion theorems proven in our previous two papers. One of the main applications is to Riemann-Roch problems for forms of higher equivariant K-theory, which we are able to…

Algebraic Geometry · Mathematics 2024-05-17 Gunnar Carlsson , Roy Joshua , Pablo Pelaez

In this article we describe the $G_{comp}\times G_{comp}$-equivariant topological $K$-ring of a {\em cellular} toroidal embedding $\mathbb{X}$ of a complex connected reductive algebraic group $G$. In particular, our results extend the…

Algebraic Geometry · Mathematics 2025-06-11 Alexis Tchoudjem , V. Uma

Let T be the circle and A be a T-C*-algebra. Then the T-equivariant K-theory of A is a module over the representation ring of the circle. The latter is a Laurent polynomial ring. Using the support of the module as an invariant, and…

K-Theory and Homology · Mathematics 2013-03-21 Heath Emerson

We prove that structure constants related to Hecke algebras at roots of unity are special cases of k-Littlewood-Richardson coefficients associated to a product of k-Schur functions. As a consequence, both the 3-point Gromov-Witten…

Combinatorics · Mathematics 2007-05-23 L. Lapointe , J. Morse

We compute the Borel equivariant cohomology ring of the left $K$-action on a homogeneous space $G/H$, where $G$ is a connected Lie group, $H$ and $K$ are closed, connected subgroups and $2$ and the torsion primes of the Lie groups are units…

Algebraic Topology · Mathematics 2025-12-24 Jeffrey D. Carlson

We prove a version of Quillen's stratification theorem in equivariant homotopy theory for a finite group $G$, generalizing the classical theorem in two directions. Firstly, we work with arbitrary commutative equivariant ring spectra as…

Algebraic Topology · Mathematics 2024-11-26 Tobias Barthel , Natalia Castellana , Drew Heard , Niko Naumann , Luca Pol

We reveal a correspondence between the homological torsion of the Bianchi groups and new geometric invariants, which are effectively computable thanks to their action on hyperbolic space. We use it to explicitly compute their integral group…

K-Theory and Homology · Mathematics 2011-09-09 Alexander D. Rahm