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Using a global version of the equivariant Chern character, we describe the complexified twisted equivariant K-theory of a space with a compact Lie group action in terms of fixed-point data. We apply this to the case of a compact Lie group…

Algebraic Topology · Mathematics 2014-02-26 Daniel S. Freed , Michael J. Hopkins , Constantin Teleman

It is proved that if S^6 possesses an integrable complex structure, then there exists a 1-dimensional family of pairwise different exotic complex structures on P_3(C). This follows immediately from the main result of the paper: S^6 is not…

Algebraic Geometry · Mathematics 2007-05-23 Alan T. Huckleberry , Stefan Kebekus , Thomas Peternell

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

Proper group actions are ubiquitous in mathematics and have many of the attractive features of actions of compact groups. In this survey, we discuss proper actions of Lie groups on smooth manifolds. If the group dimension is sufficiently…

Complex Variables · Mathematics 2015-02-02 Alexander Isaev

Let G be a compact, semi-simple Lie group and H a maximal rank reductive subgroup. The irreducible representations of G can be constructed as spaces of harmonic spinors with respect to a Dirac operator on the homogeneous space G/H twisted…

Differential Geometry · Mathematics 2007-05-23 Gregory D. Landweber

We study the Duflot filtration on the Borel equivariant cohomology of smooth manifolds with a smooth $p$-torus action. We axiomatize the filtration and prove analog of several structural results about equivariant cohomology rings in this…

Algebraic Topology · Mathematics 2018-10-18 James C. Cameron

We construct a universal continuous invariant bilinear form for the Lie algebra of compactly supported sections of a Lie algebra bundle in a topological sense. Moreover we construct a universal continuous central extension of a current…

Rings and Algebras · Mathematics 2014-02-03 Jan Milan Eyni

In two seminal papers Kontsevich used a construction called_graph homology_ as a bridge between certain infinite dimensional Lie algebras and various topological objects, including moduli spaces of curves, the group of outer automorphisms…

Quantum Algebra · Mathematics 2010-08-25 Jim Conant , Karen Vogtmann

We study compact complex manifolds $M$ admitting a conformal holomorphic Riemannian structure invariant under the action of a complex semi-simple Lie group $G$. We prove that if the group $G$ acts transitively and essentially, then $M$ is…

Differential Geometry · Mathematics 2024-05-07 Mehdi Belraouti , Mohamed Deffaf , Yazid Raffed , Abdelghani Zeghib

Consider a compact group $G$ acting on a real or complex Banach Lie group $U$, by automorphisms in the relevant category, and leaving a central subgroup $K\le U$ invariant. We define the spaces ${}_KZ^n(G,U)$ of $K$-relative continuous…

Operator Algebras · Mathematics 2023-12-27 Alexandru Chirvasitu , Jun Peng

We study a natural Dirac operator on a Lagrangian submanifold of a K\"ahler manifold. We first show that its square coincides with the Hodge-de Rham Laplacian provided the complex structure identifies the Spin structures of the tangent and…

Differential Geometry · Mathematics 2009-11-10 Nicolas Ginoux

For a simply connected (non-nilpotent) solvable Lie group $G$ with a lattice $\Gamma$ the de Rham and Dolbeault cohomologies of the solvmanifold $G/\Gamma$ are not in general isomorphic to the cohomologies of the Lie algebra $\mathfrak g$…

Differential Geometry · Mathematics 2016-05-24 Sergio Console , Anna Fino , Hisashi Kasuya

We classify those manifolds of positive euler characteristic on which a lie group G acts with cohomogeneity one, where G is classical simple

Differential Geometry · Mathematics 2012-10-26 Philipp Frank

In this paper, extending the results in \cite{F}, we compute Adams operations on twisted $K$-theory of connected, simply-connected and simple compact Lie groups $G$, in both equivariant and nonequivariant settings.

Algebraic Topology · Mathematics 2024-03-26 Chi-Kwong Fok

On a smooth closed oriented $4$-manifold $M$ with a smooth action by a compact Lie group $G$, we define a $G$-monopole class as an element of $H^2(M;\Bbb Z)$ which is the first Chern class of a $G$-equivariant Spin$^c$ structure which has a…

Geometric Topology · Mathematics 2014-08-28 Chanyoung Sung

Given a smooth free action of a compact connected Lie group $G$ on a smooth compact manifold $M$, we show that the space of $G$-invariant Riemannian metrics on $M$ whose automorphism group is precisely $G$ is open dense in the space of all…

Differential Geometry · Mathematics 2021-03-26 Alexandru Chirvasitu

Equivariant indices have previously been defined in cases where either the group or the orbit space in question is compact. In this paper, we develop an equivariant index without assuming the group or the orbit space to be compact. This…

K-Theory and Homology · Mathematics 2016-09-06 Peter Hochs , Yanli Song

We give an index formula for a class of Dirac operators coupled with unbounded potentials. More precisely, we study operators of the form P := D+ V, where D is a Dirac operators and V is an unbounded potential at infinity on a possibly…

K-Theory and Homology · Mathematics 2011-12-30 Catarina Carvalho , Victor Nistor

We establish an S^1-equivariant index theorem for Dirac operators on Z/k-manifolds. As an application, we generalize the Atiyah-Hirzebruch vanishing theorem for S^1-actions on closed spin manifolds to the case of Z/k-manifolds.

Differential Geometry · Mathematics 2007-05-23 Weiping Zhang

We describe simply connected compact exceptional simple Lie groups in very elementary way. We first construct all simply connected compact exceptional Lie groups G concretely. Next, we find all involutive automorphisms of G, and determine…

Differential Geometry · Mathematics 2009-02-04 Ichiro Yokota