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We define a noncommutative analogue of invariant de Rham cohomology. More precisely, for a triple $(A,\mathcal{H},M)$ consisting of a Hopf algebra $\mathcal{H}$, an $\mathcal{H}$-comodule algebra $A$, an $\mathcal{H}$-module $M$, and a…

K-Theory and Homology · Mathematics 2007-05-23 M. Khalkhali , B. Rangipour

We define a Hopf cyclic (co)homology theory in an arbitrary symmetric strict monoidal category. Thus we unify all different types of Hopf cyclic (co)homologies under one single universal theory. We recover Hopf cyclic (co)homology of module…

K-Theory and Homology · Mathematics 2007-05-23 Atabey Kaygun

In this paper we determine the rational homotopy type of the classifying space of a generic Kac-Moody group by computing its rational cohomology ring. As an application we determine the rational homology Hopf algebra of the generic…

Algebraic Topology · Mathematics 2020-05-06 Xu-an Zhao , Hongzhu Gao

Huayi Chen introduces the notion of an approximable graded algebra, which he uses to prove a Fujita-type theorem in the arithmetic setting, and asked if any such algebra is the graded ring of a big line bundle on a projective variety. This…

Algebraic Geometry · Mathematics 2026-05-27 Catriona Maclean

In his work on defining the pointed set B(G) for all local and global fields, Kottwitz introduced certain Galois gerbes and considered their 'algebraic' cohomology with values in algebraic groups. However, the gerbes so constructed are only…

Number Theory · Mathematics 2024-07-09 Jack Sempliner , Richard Taylor

We compute the cohomology ring $H^*(U,\mathbb{Z}/n\mathbb{Z})$ for $U=X\setminus S$ where $X$ is the spectrum of the ring of integers of a number field $K$ and $S$ is a finite set of finite primes. As a consequence, we obtain an efficient…

Number Theory · Mathematics 2026-01-01 Eric Ahlqvist , Magnus Carlson

In the rational cohomology of a 1-connected space a structure of $C_{\infty}$-algebra is constructed and it is shown that this object determines the rational homotopy type

Algebraic Topology · Mathematics 2008-11-12 Tornike Kadeishvili

Staic defined symmetric cohomology of groups and studied that the secondary symmetric cohomology group is corresponding to group extensions and the injectivity of the canonical map from symmetric cohomology to classical cohomology. In this…

Rings and Algebras · Mathematics 2023-07-10 Yuta Shiba , Katsunori Sanada , Ayako Itaba

An abelian arrangement is a finite set of codimension one abelian subvarieties (possibly translated) in a complex abelian variety. In this paper, we study the cohomology of the complement of an abelian arrangement. For unimodular abelian…

Algebraic Geometry · Mathematics 2018-05-10 Christin Bibby

A new method is given for computing generators of the homology groups with integer coefficients for any finite $T_0$-space. An important role in this method is played by irreducible cycles which are defined here and give rise to continuous…

Algebraic Topology · Mathematics 2018-11-13 Patrick Erik Bradley

In this paper homotopical methods for the description of subgroups determined by ideals in group rings are introduced. It is shown that in certain cases the subgroups determined by symmetric product of ideals in group rings can be described…

Group Theory · Mathematics 2012-02-07 Roman Mikhailov , Inder Bir S. Passi , Jie Wu

Electromagnetic modeling provides an interesting context to present a link between physical phenomena and homology and cohomology theories. Over the past twenty-five years, a considerable effort has been invested by the computational…

Algebraic Topology · Mathematics 2011-11-11 Paweł Dłotko , Ruben Specogna

A real toric space is a topological space which admits a well-behaved $\mathbb{Z}_2^k$-action. Real moment-angle complexes and real toric varieties are typical examples of real toric spaces. A real toric space is determined by a pair of a…

Algebraic Topology · Mathematics 2017-11-15 Suyoung Choi , Hanchul Park

We study the cup product on the Hochschild cohomology of the stack quotient [X/G] of a smooth quasi-projective variety X by a finite group G. More specifically, we construct a G-equivariant sheaf of graded algebras on X whose G-invariant…

Algebraic Geometry · Mathematics 2018-12-13 Cris Negron , Travis Schedler , Pieter Belmans , Pavel Etingof

For module algebras and module coalgebras over an arbitrary bialgebra, we define two types of bivariant cyclic cohomology groups called bivariant Hopf cyclic cohomology and bivariant equivariant cyclic cohomology. These groups are defined…

K-Theory and Homology · Mathematics 2007-05-23 Atabey Kaygun , Masoud Khalkhali

The goal of this paper is to offer a new construction of the de Rham-Witt complex of smooth varieties over perfect fields of characteristic $p>0$. We introduce a category of cochain complexes equipped with an endomorphism $F$ of underlying…

Algebraic Geometry · Mathematics 2020-02-20 Bhargav Bhatt , Jacob Lurie , Akhil Mathew

A kind of unstable homotopy theory on the category of associative rings (without unit) is developed. There are the notions of fibrations, homotopy (in the sense of Karoubi), path spaces, Puppe sequences, etc. One introduces the notion of a…

K-Theory and Homology · Mathematics 2007-05-23 Grigory Garkusha

We study the cohomology and hence $K$-theory of the aperiodic tilings formed by the so called 'cut and project' method, i.e., patterns in $d$ dimensional Euclidean space which arise as sections of higher dimensional, periodic structures.…

K-Theory and Homology · Mathematics 2016-01-20 Franz Gaehler , John Hunton , Johannes Kellendonk

We describe a Hopf ring structure on the direct sum of the cohomology groups $\bigoplus_{n \geq 0} H^* \left( W_{B_n}; \mathbb{F}_2 \right)$ of the Coxeter groups of type $B_n$, and an almost-Hopf ring structure on the direct sum of the…

Algebraic Topology · Mathematics 2023-10-04 Lorenzo Guerra

A homology and cohomology theory for topological quandles are introduced. The relation between these (co)homology groups and quandle (co)homology groups are studied. The 1 - topological quandle cocycles are used to compute state sum…

Geometric Topology · Mathematics 2022-08-03 Georgy C. Luke , B. Subhash