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We describe the integral cohomology of $X/G$ where $X$ is a compact complex manifold and $G$ a cyclic group of prime order with only isolated fixed points. As a preliminary step, we investigate the integral cohomology of toric blow-ups of…

Algebraic Geometry · Mathematics 2025-03-26 Grégoire Menet

Let $G$ be a compact Lie group. We prove that if $V$ and $W$ are orthogonal $G$-representations such that $V^G=W^G=\{0\}$, then a $G$-equivariant map $S(V) \to S(W)$ exists provided that $\dim V^H \leq \dim W^H$ for any closed subgroup…

Algebraic Topology · Mathematics 2018-01-09 Zbigniew Błaszczyk , Wacław Marzantowicz , Mahender Singh

For $S$ a closed surface of genus $g\geq2$, we construct a canonical diffeomorphism from the degree $3$ Fock-Thomas space $\mathcal{T}^3(S)$ of higher complex structures to the $\text{SL}(3,\mathbb{R})$ Hitchin component. Our construction…

Geometric Topology · Mathematics 2022-04-12 Alexander Nolte

For a homogeneous space X of a connected algebraic group G (with connected stabilizers) over a field k of characteristic zero, we construct a canonical complex of Galois modules of length 3 and a canonical isomorphism between an…

Algebraic Geometry · Mathematics 2010-11-24 Cyril Demarche

We consider orbit configuration spaces associated to finite groups acting freely by orientation preserving homeomorphisms on the $2$-sphere minus a finite number of points. Such action is equivalent to a homography action of a finite…

Algebraic Topology · Mathematics 2020-07-06 Mohamad Maassarani

In this paper, we define the weighted homogeneous space (WHS), denoted by $\frac{G}{P}[\psi_H]$ where $\psi_H$ is weight function defined on the set of simple roots of $G$, by an element $H$ in the highest Weyl chamber. The weight function…

Representation Theory · Mathematics 2021-11-09 Mohammad Reza Rahmati , Gerardo Flores

Let $G/K$ be an irreducible Hermitian symmetric spaces of compact type with the standard homogeneous complex structure. Then the real symplectic manifold $(T^*(G/K),\Omega)$ has the natural complex structure $J^-$. We construct all…

Differential Geometry · Mathematics 2015-06-26 I. V. Mykytyuk

An \emph{affine subtorus} of the compact torus $T=(S^1)^n$ is a translated copy of a Lie subgroup. Given a finite collection $T_1,\ldots, T_k$ of such subtori, and a prime $p$, we describe an explicit chain complex that calculates the group…

Algebraic Topology · Mathematics 2026-01-14 Alexey G. Gorinov , Alexander V. Zakharov

Let X be a normal affine T-variety of complexity at most one over a perfect field k, where T stands for the split algebraic torus. Our main result is a classification of additive group actions on X that are normalized by the T-action. This…

Algebraic Geometry · Mathematics 2016-01-28 Kevin Langlois , Alvaro Liendo

The equivariant bootstrap class in the Kasparov category of actions of a finite group G consists of those actions that are equivalent to one on a Type I C*-algebra. Using a result by Arano and Kubota, we show that this bootstrap class is…

Operator Algebras · Mathematics 2026-02-25 Ralf Meyer , George Nadareishvili

Let $G$ be a connected reductive affine algebraic group defined over the complex numbers, and $K\subset G$ be a maximal compact subgroup. Let $X , Y$ be irreducible smooth complex projective varieties and $f: X \rightarrow Y$ an algebraic…

Algebraic Geometry · Mathematics 2015-07-17 Indranil Biswas , Carlos Florentino

Let $G$ be a complex semi-simple Lie group and form its maximal flag manifold $\mathbb{F}=G/P=U/T$ where $P$ is a minimal parabolic subgroup, $U$ a compact real form and $T=U\cap P$ a maximal torus of $U$. The aim of this paper is to study…

Differential Geometry · Mathematics 2020-04-01 Carlos A. B. Varea , Luiz A. B. San Martin

HyperK\"ahler spaces, including manifolds, orbifolds and conical singularities play an important role in superstring/$M$-theory and gauge theories as well as in differential and algebraic geometry. In this paper we provide hundreds of new…

High Energy Physics - Theory · Physics 2025-01-08 Daniel Andrew Baldwin , Bobby Samir Acharya

Given a torus action on a compact space X, a fundamental result of Borel and Atiyah-Segal asserts that the equivariant cohomology of X is concentrated in the fixed locus X^T, up to inverting enough Chern classes. We prove an analogue for…

Algebraic Geometry · Mathematics 2023-08-04 Adeel A. Khan , Charanya Ravi

We introduce a Hopf algebroid associated to a proper Lie group action on a smooth manifold. We prove that the cyclic cohomology of this Hopf algebroid is equal to the de Rham cohomology of invariant differential forms. When the action is…

Differential Geometry · Mathematics 2010-02-25 Xiang Tang , Yi-Jun Yao , Weiping Zhang

Using the Witten deformation and localization algebra techniques, we compute the $G$-equivariant $K$-homology class of the de Rham operator on a proper cocompact $G$-spin manifold, where $G$ is an almost connected Lie group. By applying a…

Operator Algebras · Mathematics 2025-08-22 Hongzhi Liu , Hang Wang , Zijing Wang , Shaocong Xiang

We prove that any holomorphic locally homogeneous geometric structure on a complex torus, modelled on a complex homogeneous surface, is translation invariant. We conjecture that this result is true is any dimension. In higher dimension we…

Differential Geometry · Mathematics 2019-11-12 Sorin Dumitrescu , Benjamin McKay

Noncommutative K\"ahler structures were recently introduced as an algebraic framework for studying noncommutative complex geometry on quantum homogeneous spaces. In this paper, we introduce the notion of a \emph{compact quantum homogeneous…

Quantum Algebra · Mathematics 2026-03-17 Biswarup Das , Réamonn Ó Buachalla , Petr Somberg

In this short note, we compute the rational $C_{2^n}$-equivariant stable stems and give minimal presentations for the $RO(C_{2^n})$-graded Bredon cohomology of the equivariant classifying spaces $B_{C_{2^n}}S^1$ and $B_{C_{2^n}}\Sigma_2$…

Algebraic Topology · Mathematics 2021-04-27 Nick Georgakopoulos

In this paper, we study invariant Poisson structures on homogeneous manifolds, which serve as a natural generalization of homogeneous symplectic manifolds previously explored in the literature. Our work begins by providing an algebraic…

Differential Geometry · Mathematics 2025-04-10 Abdelhak Abouqateb , Charif Bourzik