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Let $C_2$ denote the cyclic group of order two. Given a manifold with a $C_2$-action, we can consider its equivariant Bredon $RO(C_2)$-graded cohomology. In this paper, we develop a theory of fundamental classes for equivariant submanifolds…

Algebraic Topology · Mathematics 2021-12-01 Christy Hazel

We develop a theory of $C_p$-Green functors of Lie type, unifying the axiomatic framework of Green functors with the structure of Lie algebras under the action of a cyclic group $C_p$ of prime order. Extending classical notions from…

Rings and Algebras · Mathematics 2025-07-11 Tarik Anowar , Satyendra Kumar Mishra , Ripan Saha

We give explicit MacPherson cycles for the Chern-MacPherson class of a closed affine algebraic variety $X$ and for any constructible function $\alpha$ with respect to a complex algebraic Whitney stratification of $X$. We define generalized…

Algebraic Geometry · Mathematics 2010-03-30 Joerg Schuermann , Mihai Tibar

The aim of this note is to point out that Chern characters can be computed using curvatures o ``super-connections up to homotopy'. We also present an application to the vanishing theorem for Lie algebroids which is at the origin of new…

Differential Geometry · Mathematics 2007-05-23 Marius Crainic

A bivariant functor is defined on a category of *-algebras and a category of operator ideals, both with actions of a second countable group $G$, into the category of abelian monoids. The element of the bivariant functor will be…

K-Theory and Homology · Mathematics 2011-02-01 Magnus Goffeng

We use group representation theory to give algebraic formulae to compute complete transversals of singularities of vector fields, either in the nonsymmetric or in the reversible equivariant contexts. This computation produces normal forms…

Dynamical Systems · Mathematics 2013-09-10 Miriam Manoel , Iris de Oliveira Zeli

Let $\Gamma$ be a finite group acting linearly on a vector space $V$. We compute the Lie algebra cohomology of the Lie algebra of $\Gamma$-invariant formal vector fields on $V$. We use this computation to define characteristic classes for…

Representation Theory · Mathematics 2007-05-23 Ilya Shapiro , Xiang Tang

In this paper we construct a Chern-Weil isomorphism for the equivariant Brauer group of R^n-actions on a principal torus bundle, where the target for this isomorphism is a "dimensionally reduced" Cech cohomology group. From this point of…

Operator Algebras · Mathematics 2011-09-16 Peter Bouwknegt , Alan Carey , Rishni Ratnam

Given a non compact semisimple Lie group $G$ we describe all homogeneous spaces $G/L$ carrying an invariant almost K\"ahler structure $(\omega,J)$. When $L$ is abelian and $G$ is of classical type, we classify all such spaces which are…

Differential Geometry · Mathematics 2018-12-07 Dmitri V. Alekseevsky , Fabio Podestà

In this note we prove a conjecture of Kashiwara, which states that the Euler class of a coherent analytic sheaf F on a complex manifold X is the product of the Chern character of F with the Todd class of X. As a corollary, we obtain a…

Algebraic Geometry · Mathematics 2017-10-10 Julien Grivaux

We give a short proof of the fact that the Chern classes for singular varieties defined by Marie-Helene Schwartz by means of "radial frames" agree with the functorial notion defined by Robert MacPherson.

Algebraic Geometry · Mathematics 2012-04-11 Paolo Aluffi , Jean-Paul Brasselet

We compute the equivariant cohomology of complex projective spaces associated to finite-dimensional representations of $C_2$, using ordinary cohomology graded on representations of the fundamental groupoid, with coefficients in the Burnside…

Algebraic Topology · Mathematics 2022-05-17 Steven R. Costenoble , Thomas Hudson , Sean Tilson

An odd vector field $Q$ on a supermanifold $M$ is called homological, if $Q^2=0$. The operator of Lie derivative $L_Q$ makes the algebra of smooth tensor fields on $M$ into a differential tensor algebra. In this paper, we give a complete…

Mathematical Physics · Physics 2010-11-09 E. Mosman , A. Sharapov

In this paper, we study the homogeneous components of the Chern--Schwartz--MacPherson (CSM) classes of Schubert cells. We prove that, under suitable conditions, each such component is represented by an irreducible subvariety. In particular,…

Algebraic Geometry · Mathematics 2026-03-27 Yuxiang Liu , Artan Sheshmani , Shing-Tung Yau

In this article, we construct Chern classes in rational Deligne cohomology for coherent sheaves on a smooth complex compact manifold. We prove that these classes verify the functoriality property under pullbacks, the Whitney formula and the…

Algebraic Geometry · Mathematics 2017-10-10 Julien Grivaux

We generalize the classical semiregularity theorem of Buchweitz and Flenner to the setting of noncommutative algebraic geometry, with group actions. This applies in particular to twisted derived categories, in which case it answers a…

Algebraic Geometry · Mathematics 2026-04-02 Alexander Perry

This note shows the compatibility of the differential geometric and the topological formulations of equivariant characteristic classes for a compact connected Lie group action.

Differential Geometry · Mathematics 2007-05-23 Raoul Bott , Loring W. Tu

A cocycle $\Omega: P \times G \to H$ taking values in a Lie group $H$ for a free right action of $G$ on $P$ defines a principal bundle $Q$ with the structure group $H$ over $P/G.$ The Chern character of a vector bundle associated to $Q$…

Differential Geometry · Mathematics 2012-05-11 Jouko Mickelsson

We define degeneracy loci for vector bundles with structure group $G_2$, and give formulas for their cohomology (or Chow) classes in terms of the Chern classes of the bundles involved. When the base is a point, such formulas are part of the…

Algebraic Geometry · Mathematics 2011-09-02 Dave Anderson

For two complex vector bundles admitting a homomorphism between them, a Poincar\'e-Hopf formula for the difference of the Chern character numbers of these two vector bundles with isolated singularities is established by Huitao Feng, Weiping…

Differential Geometry · Mathematics 2022-10-18 Xu Chen