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Related papers: Bigraded Equivariant Cohomology of Real Quadrics

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We are interested in computing the Bredon cohomology with coefficients in the constant Mackey functor $\underline{ \mathbb{F}_2}$ for equivariant $\text{Rep}(C_2)$ spaces, in particular for Grassmannian manifolds of the form…

Algebraic Topology · Mathematics 2025-03-14 Eric Hogle

We compute the $RO(C_p \times C_p)$-graded Bredon cohomology of equivariant universal and classifying spaces associated to families of subgroups, with coefficients in the constant Mackey functor $\underline{\mathbb{F}_p}$. An explicit…

Algebraic Topology · Mathematics 2026-03-12 Surojit Ghosh , Ankit Kumar

In this, the second of three papers about $C_2$-equivariant complex quadrics, we calculate the equivariant ordinary cohomology of smooth symmetric quadrics graded on the representation ring of $\Pi BU(1)$ and with coefficients in the…

Algebraic Topology · Mathematics 2025-11-19 Steven R. Costenoble , Thomas Hudson

We study the $RO(G)$-graded Bredon cohomology of a point in the case where $G$ is a cyclic group of odd order, expanding on the information provided by previous studies. Our methods center on the purely algebraic aspects of this matter,…

Algebraic Topology · Mathematics 2026-02-24 Daniel Dugger , Christy Hazel

We calculate the representation-graded Bredon homology rings of all elementary abelian 2-groups with coefficients in the constant mod-2 Mackey functor. We exhibit minimal presentations for these rings as quotients of the polynomial algebra…

Algebraic Topology · Mathematics 2025-11-05 Markus Hausmann , Stefan Schwede

Over the real numbers with $\Z/2-$coefficients, we compute the $C_2$-equivariant Borel motivic cohomology ring, the Bredon motivic cohomology groups and prove that the Bredon motivic cohomology ring of the real numbers is a proper subring…

Algebraic Geometry · Mathematics 2025-05-28 Bill Deng , Mircea Voineagu

This paper determines the RO(G)-graded Eilenberg-MacLane cohomology of the real, infinite, equivariant Grassmannians in the case G=Z/2. Possible connections with motivic characteristic classes for quadratic bundles are briefly discussed.

Algebraic Topology · Mathematics 2015-05-27 Daniel Dugger

Let $B$ denote the upper triangular subgroup of $SL_2(C)$, $T$ its diagonal torus and $U$ its unipotent radical. A complex projective variety $Y$ endowed with an algebraic action of $B$ such that the fixed point set $Y^U$ is a single point,…

Algebraic Geometry · Mathematics 2007-05-23 Michel Brion , James B. Carrell

The additive structure of the $RO(C_{pq})$-graded Bredon cohomology $S^0$ with coefficients in the constant Mackey functor was computed in \cite{BG19}. Using that computation, the ring structure in the positive degrees has been computed…

Algebraic Topology · Mathematics 2024-04-25 Surojit Ghosh

By a $B$-regular variety, we mean a smooth projective variety over $C$ admitting an algebraic action of the upper triangular Borel subgroup $B \subset SL_2(C)$ such that the unipotent radical in $B$ has a unique fixed point. A result of M.…

Algebraic Geometry · Mathematics 2008-09-09 James B. Carrell , Kiumars Kaveh

We obtain a characterization of Maximal and Galois-Maximal $C_2$-spaces (including real algebraic varieties) in terms of $\operatorname{RO}(C_2)$-graded cohomology with coefficients in the constant Mackey functor $\underline{\mathbf{F}}_2$,…

Algebraic Geometry · Mathematics 2023-10-27 Pedro F. dos Santos , Carlos Florentino , Javier Orts

Let $C_n$ denote a cyclic group of order $n$. In this paper we investigate modules and chain complexes over the constant integral Mackey functor $\underline{\mathbb{Z}}$ and perform some related homological calculations. Along the way we…

Algebraic Topology · Mathematics 2026-02-24 Daniel Dugger , Christy Hazel

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

We describe the equivariant cohomology ring of rationally smooth projective embeddings of reductive groups. These embeddings are the projectivizations of reductive monoids. Our main result describes their equivariant cohomology in terms of…

Algebraic Geometry · Mathematics 2015-07-21 Richard Gonzales

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 prove that, over a perfect field, Bredon motivic cohomology can be computed by Suslin-Friedlander complexes of equivariant equidimensional cycles. Partly based on this result we completely identify Bredon motivic cohomology of a…

K-Theory and Homology · Mathematics 2019-07-12 Mircea Voineagu

In this paper, we compute the $RO(C_n)$-graded coefficient ring of equivariant cohomology for cyclic groups $C_n$, in the case of Burnside ring coefficients, and in the case of constant coefficients. We use the invertible Mackey functors…

Algebraic Topology · Mathematics 2024-03-04 Samik Basu , Pinka Dey

We prove equivariant versions of the Beilinson-Lichtenbaum conjecture for Bredon motivic cohomology of smooth complex and real varieties with an action of the group of order two. This identifies equivariant motivic and topological…

Algebraic Topology · Mathematics 2018-03-20 Jeremiah Heller , Mircea Voineagu , Paul Arne Ostvaer

In this paper we study the local cohomology of all finitely generated bigraded modules over a standard bigraded polynomial ring which have only one nonvanishing local cohomology with respect to one of the irrelevant bigraded ideals.

Commutative Algebra · Mathematics 2008-03-25 Ahad Rahimi

In this expository article we give a categorical definition of the integral cohomology ring of a stack. We show that for quotient stacks the categorical cohomology may be identified with equivariant cohomology. Via this identification we…

Algebraic Geometry · Mathematics 2011-08-08 Dan Edidin
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