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The main result of this paper is an application of the topology of the space $Q(X)$ to obtain results for the cohomology of the symmetric group on $d$ letters, $\Sigma_d$, with `twisted' coefficients in various choices of Young modules and…

Representation Theory · Mathematics 2009-12-29 Frederick R. Cohen , David J. Hemmer , Daniel K. Nakano

Let $G$ be an algebraic group over a field $k$, and $M$ and $N$ be $G$-modules. In 1961, Hochschild showed how one can define the cohomology groups $\text{Ext}_{G}^{i}(M,N)$. Kimura, in 1965, showed that one can generalize this to get…

Group Theory · Mathematics 2026-02-05 Gabriel T. Loos

Let G be a complex reductive group and X a projective spherical G-variety. Moreover, assume that the subalgebra A of the cohomology ring H^*(X, R) generated by the Chern classes of line bundles has Poincare duality. We give a description of…

Algebraic Geometry · Mathematics 2012-04-04 Kiumars Kaveh

We take initial steps towards a general framework for constructing logical gates in general quantum CSS codes. Viewing CSS codes as cochain complexes, we observe that cohomology invariants naturally give rise to diagonal logical gates. We…

We compute the cohomology with group ring coefficients of the complement of a finite collection of affine hyperplanes in a finite dimensional complex vector space. It is nonzero in exactly one degree, namely the degree equal to the rank of…

Algebraic Topology · Mathematics 2010-02-23 Michael W Davis , Tadeusz Januszkiewicz , Ian J Leary , Boris Okun

Given a Hopf algebra A, there exist various cohomology theories for the category of Hopf bimodules over A, introduced by M. Gerstenhaber and S.D. Schack, and by C. Ospel. We prove, when A is finite dimensional, that they are equal to the…

Quantum Algebra · Mathematics 2009-10-31 Rachel Taillefer

The codomain category of a generalized homology theory is the category of modules over a ring. For an abelian category A, an A-valued (generalized) homology theory is defined by formally replacing the category of modules with the category…

Algebraic Topology · Mathematics 2020-05-12 Minkyu Kim

Let $G$ be a split connected reductive group over the ring of integers of a finite unramified extension $K$ of $\mathbf{Q}_p$. Under a standard assumption on the Coxeter number of $G$, we compute the cohomology algebra of $G(\mathcal{O}_K)$…

Number Theory · Mathematics 2025-07-21 Andrea Dotto , Bao V. Le Hung

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

We show that the cohomology ring of a finite-dimensional complex pointed Hopf algebra with an abelian group of group-like elements is finitely generated. Our strategy has three major steps. We first reduce the problem to the finite…

Quantum Algebra · Mathematics 2021-08-03 Nicolás Andruskiewitsch , Iván Angiono , Julia Pevtsova , Sarah Witherspoon

We compute the cohomology ring of a generalised type of configuration space of points in $\mathbb{R}^r$. This configuration space is indexed by a graph. In the case the graph is complete the result is known and it is due to Arnold and…

Algebraic Topology · Mathematics 2020-04-20 Marcel Bökstedt , Erica Minuz

We develop an approach to calculating the cup and cap products on Hochschild cohomology and homology of curved algebras associated with polynomials and their finite abelian symmetry groups. For polynomials with isolated critical points, the…

Algebraic Geometry · Mathematics 2017-08-29 Dmytro Shklyarov

In this paper, we compute the rational cohomology groups of the classifying space of a simply connected Kac-Moody group of infinite type. The fundamental principle is "from finite to infinite". That is, for a Kac-Moody group G(A) of…

Algebraic Topology · Mathematics 2021-12-21 Zhao Xu-an , Gao Hongzhu , Ruan Yangyang

We prove explicit and elementary formulas for the group homology and cohomology of a finite group with coefficients in any module. We describe in elementary terms the cohomology algebra $H^*(G,k)$ as a graded algebra for a finite group $G$…

Group Theory · Mathematics 2015-07-16 Sergei O. Ivanov , Nikolay N. Mostovsky

Inspired by a question raised by Eisenbud-Musta\c{t}\u{a}-Stillman regarding the injectivity of maps from ${\rm Ext}$ modules to local cohomology modules and the work by the third author with Pham, we introduce a class of rings which we…

Commutative Algebra · Mathematics 2019-01-09 Hailong Dao , Alessandro De Stefani , Linquan Ma

Over the complex numbers, the complement of a collection of hyperplanes is a widely-studied object; the cohomology ring, in particular, is known to have a structure depending only on the combinatorial properties of the intersection of…

Algebraic Topology · Mathematics 2015-08-25 William Schlieper

Let G be a reductive linear algebraic group over a field k. Let A be a finitely generated commutative k-algebra on which G acts rationally by k-algebra automorphisms. Invariant theory tells that the ring of invariants A^G=H^0(G,A) is…

Representation Theory · Mathematics 2019-12-19 Antoine Touzé , Wilberd van der Kallen

We calculate the rational cohomology of the classifying space of the diffeomorphism group of the manifolds $U_{g,1}^n:= \#^g(S^n \times S^{n+1})\setminus \mathrm{int}{D^{2n+1}}$, for large $g$ and $n$, up to approximately degree $n$. The…

Algebraic Topology · Mathematics 2024-02-21 Johannes Ebert , Jens Reinhold

A cohomology theory for lambda-rings is developed. This is then applied to study deformations of lambda-rings.

Algebraic Topology · Mathematics 2007-05-23 Donald Yau

We compute quantum cohomology ring of elliptic $\mathbb{P}^1$ orbifolds via orbi-curve counting. The main technique is the classification theorem which relates holomorphic orbi-curves with certain orbifold coverings. The countings of…

Symplectic Geometry · Mathematics 2014-06-17 Hansol Hong , Hyung-Seok Shin