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We show that the center of a flat graded deformation of a standard Koszul algebra behaves in many ways like the torus-equivariant cohomology ring of an algebraic variety with finite fixed-point set. In particular, the center acts by…

Rings and Algebras · Mathematics 2022-11-18 Tom Braden , Anthony Licata , Christopher Phan , Nicholas Proudfoot , Ben Webster

In this paper we work with a series whose coefficients are the Euler characteristic of Chow varieties of a given projective variety. For varieties where the Cox ring is defined, it is easy to see that in this case the ring associated to the…

Algebraic Geometry · Mathematics 2015-07-27 Xi Chen , E. Javier Elizondo , Yanhong Yang

The coefficient algebra of a finite-dimensional Lie algebra on a finite-dimensional representation is defined as the subalgebra generated by all coefficients of the corresponding characteristic polynomial. We explore connections between…

Commutative Algebra · Mathematics 2025-11-14 Yin Chen , Runxuan Zhang

Let $X$ be a complex toric variety equipped with the action of an algebraic torus $T$, and let $G$ be a complex linear algebraic group. We classify all $T$-equivariant principal $G$-bundles $\mathcal{E}$ over $X$ and the morphisms between…

Algebraic Geometry · Mathematics 2022-11-08 Jyoti Dasgupta , Bivas Khan , Indranil Biswas , Arijit Dey , Mainak Poddar

For $G$ a finite group, we show that functions on fields for the 2-dimensional supersymmetric sigma model with background $G$-symmetry determine cocycles for complex analytic $G$-equivariant elliptic cohomology. Similar structures in…

Algebraic Topology · Mathematics 2020-10-13 Daniel Berwick-Evans

We describe the equivariant K-groups of a family of generalized Steinberg varieties that interpolates between the Steinberg variety of a reductive, complex algebraic group and its nilpotent cone in terms of the extended affine Hecke algebra…

Representation Theory · Mathematics 2013-11-26 J. Matthew Douglass , Gerhard Roehrle

The Cox ring of a so-called Mori Dream Space (MDS) is finitely generated and it is graded over the divisor class group. Hence the spectrum of the Cox ring comes with an action of an algebraic torus whose GIT quotient is the variety in…

Algebraic Geometry · Mathematics 2009-11-30 Klaus Altmann , Jarek Wisniewski

Given a commutative ring $R$, a $\pi_1$-$R$-equivalence is a continuous map of spaces inducing an isomorphism on fundamental groups and an $R$-homology equivalence between universal covers. When $R$ is an algebraically closed field, Raptis…

Algebraic Topology · Mathematics 2025-04-08 Sofía Martínez Alberga , Manuel Rivera

We present a new geometric interpretation of equivariant cohomology in which one replaces a smooth, complex $G$-variety $X$ by its associated arc space $J_{\infty} X$, with its induced $G$-action. This not only allows us to obtain geometric…

Algebraic Geometry · Mathematics 2014-02-18 Dave Anderson , Alan Stapledon

Let $G$ be a finite $p$-group and $k$ a field of characteristic $p>0$. We show that $G$ has a \emph{non-linear} faithful action on a polynomial ring $U$ of dimension $n=\mathrm{log}_p(|G|)$ such that the invariant ring $U^G$ is also…

Representation Theory · Mathematics 2014-02-26 Peter Fleischmann , Chris Woodcock

Let X be a smooth simplicial toric variety. Let Z be the set of T-fixed points of X. We construct a filtration for A(Z), the ring of complex-valued functions on Z, such that Gr A(Z) is isomorphic to the cohomology algebra of X. This is the…

Algebraic Geometry · Mathematics 2007-05-23 Kiumars Kaveh

Let $X(Q,\Lambda)$ be a quasitoric manifold associated to a simple convex polytope $Q$ and characteristic function $\Lambda$. Let $T\cong (\mathbb{S}^1)^n$ denote the compact $n$-torus acting on $X=X(Q,\Lambda)$. The main aim of this…

Algebraic Topology · Mathematics 2018-05-30 Jyoti Dasgupta , Bivas Khan , V. Uma

We compute the Chow ring of a quasi-split geometrically almost simple algebraic group assuming the coefficients to be a field. This extends the classical computation for split groups done by Kac to the non-split quasi-split case. For the…

Algebraic Geometry · Mathematics 2024-10-08 Alexey Ananyevskiy , Nikita Geldhauser

Let $G$ be a compact connected Lie group and $T$ be its maximal torus. The homogeneous space $G/T$ is called the (complete) flag manifold. One of the main goals of the {\em equivariant Schubert calculus} is to study the $T$-equivariant…

Algebraic Topology · Mathematics 2015-09-16 Shizuo Kaji

This paper shows that the integral equivariant cohomology Chern numbers completely determine the equivariant geometric unitary bordism classes of closed unitary $G$-manifolds, which gives an affirmative answer to the conjecture posed by…

Algebraic Topology · Mathematics 2019-03-19 Zhi Lü , Wei Wang

Let $U$ be a graded unipotent group over the complex numbers, in the sense that it has an extension $\hat{U}$ by the multiplicative group such that the action of the multiplicative group by conjugation on the Lie algebra of $U$ has all its…

Algebraic Geometry · Mathematics 2020-01-22 Gergely Bérczi , Brent Doran , Thomas Hawes , Frances Kirwan

Let $U_\zeta$ be the quantum group (Lusztig form) associated to the simple Lie algebra $\mathfrak{g}$, with parameter $\zeta$ specialized to an $\ell$-th root of unity in a field of characteristic $p>0$. In this paper we study certain…

Representation Theory · Mathematics 2011-07-13 Christopher M. Drupieski

We give a proper definition of the multiplicative structure of the following rings: the Cox ring of invertible sheaves on a general algebraic stack; and the Cox ring of rank one reflexive sheaves on a normal and excellent algebraic stack.…

Algebraic Geometry · Mathematics 2024-01-04 Andreas Hochenegger , Elena Martinengo , Fabio Tonini

Suppose a group $\Gamma$ acts on a scheme $X$ and a Lie superalgebra $\mathfrak{g}$. The corresponding equivariant map superalgebra is the Lie superalgebra of equivariant regular maps from $X$ to $\mathfrak{g}$. We classify the irreducible…

Representation Theory · Mathematics 2015-05-15 Alistair Savage

The aim of this paper is two fold: First to study finite groups $G$ of automorphisms of the homogenized Weyl algebra $B_{n}$, the skew group algebra $B_{n}\ast G$, the ring of invariants $B_{n}^{G}$, and the relations of these algebras with…

Rings and Algebras · Mathematics 2012-11-06 Roberto Martinez-Villa , Jeronimo Mondragon