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An operad describes a category of algebras and a (co)homology theory for these algebras may be formulated using the homological algebra of operads. A morphism of operads $f:\mathcal{O}\rightarrow\mathcal{P}$ describes a functor allowing a…

Rings and Algebras · Mathematics 2014-03-20 James Griffin

We reveal a correspondence between the homological torsion of the Bianchi groups and new geometric invariants, which are effectively computable thanks to their action on hyperbolic space. We use it to explicitly compute their integral group…

K-Theory and Homology · Mathematics 2011-09-09 Alexander D. Rahm

We develop a notion of covariant differential calculus for Hopf algebroids. As a byproduct, we prove analogues of the fundamental theorem of Hopf modules and a Takeuchi-Schneider equivalence in the realm of Hopf algebroids. The resulting…

Quantum Algebra · Mathematics 2026-05-12 Niels Kowalzig , Thomas Weber

We introduce partial (co)actions of a Hopf algebra $H$ on an algebra. To this end, we introduce first the notion of lax coring, generalizing Wisbauer's notion of weak coring. We also have the dual notion of lax ring. Several duality results…

Rings and Algebras · Mathematics 2008-12-09 S. Caenepeel , K. Janssen

In 1998, Goresky, Kottwitz, and MacPherson showed that for certain projective varieties X equipped with an algebraic action of a complex torus T, the equivariant cohomology ring H_T(X) can be described by combinatorial data obtained from…

Algebraic Topology · Mathematics 2007-05-23 Megumi Harada , Andre Henriques , Tara S. Holm

We investigate models of algebraic theories in the category of cocommutative coalgebras over a field. We establish some of their categorical properties, similar to those of algebraic varieties. We introduce a class of categories of…

Category Theory · Mathematics 2025-11-12 Maria Bevilacqua

We use sheaf theory and the six operations to define and study the (equivariant) homology of stacks. The construction makes sense in the algebraic, complex-analytic, or even topological categories.

Algebraic Topology · Mathematics 2025-06-06 Adeel A. Khan

In this note we recall some recent progress in understanding the representation theory of *-algebras over rings C = R(i) where R is ordered and i^2 = -1. The representation spaces are modules over auxiliary *-algebras with inner products…

Quantum Algebra · Mathematics 2009-01-28 Stefan Waldmann

In recent work, Hess and Shipley defined a theory of topological coHochschild homology (coTHH) for coalgebras. In this paper we develop computational tools to study this new theory. In particular, we prove a Hochschild-Kostant-Rosenberg…

Algebraic Topology · Mathematics 2023-03-15 Anna Marie Bohmann , Teena Gerhardt , Amalie Høgenhaven , Brooke Shipley , Stephanie Ziegenhagen

Equivariant cohomology is suggested as an alternative algebraic framework for the definition of topological field theories constructed by E. Witten circa 1988. It also enlightens the classical Faddeev Popov gauge fixing procedure.

High Energy Physics - Theory · Physics 2007-05-23 Raymond Stora

We define an equivariant $K_0$-theory for \textit{Yetter-Drinfeld} algebras over a Hopf algebra with an invertible antipode. We then show that this definition can be generalized to all Hopf-module algebras. We show that there exists a…

K-Theory and Homology · Mathematics 2007-05-23 R. Akbarpour , M. Khalkhali

We determine the structure of the equivariant cohomology and $K$-theory of Bott towers. By restriction, we obtain similar results for Bott-Samelson varieties. This results allow us to describe more precisely the equivariant cohomology and…

Algebraic Geometry · Mathematics 2007-05-23 Matthieu Willems

We introduce a notion of "hopfish algebra" structure on an associative algebra, allowing the structure morphisms (coproduct, counit, antipode) to be bimodules rather than algebra homomorphisms. We prove that quasi-Hopf algebras are examples…

Quantum Algebra · Mathematics 2010-04-13 Xiang Tang , Alan Weinstein , Chenchang Zhu

In this letter we give an overview on recent developments in representation theory of star product algebras. In particular, we relate the *-representation theory of *-algebras over rings C = R(i) with an ordered ring R and i^2 = -1 to the…

Quantum Algebra · Mathematics 2009-11-10 Stefan Waldmann

For a $C^{*}$-category with a strict $G$-action we construct examples of equivariant coarse homology theories. To this end we first introduce versions of Roe categories of objects in $C^{*}$-categories which are controlled over bornological…

K-Theory and Homology · Mathematics 2023-06-21 Ulrich Bunke , Alexander Engel

Cohomology and deformation theories are developed for Poisson algebras starting with the more general concept of a Leibniz pair, namely of an associative algebra $A$ together with a Lie algebra $L$ mapped into the derivations of $A$. A…

q-alg · Mathematics 2016-09-08 M. Flato , M. Gerstenhaber , A. A. Voronov

We introduce the notion of \emph{topo-symmetric extensions} of topological groups, a new generalization of classical group extensions that incorporates both topological and symmetry constraints. We define morphisms between such extensions,…

General Mathematics · Mathematics 2025-10-02 Es-said En-naoui

We introduce a cohomology theory that classifies differential objects that arise from Picard-Vessiot theory, using the differential Hopf-Galois descent. To do this, we provide an explicit description of Picard-Vessiot theory in terms of…

Rings and Algebras · Mathematics 2023-10-05 Man Cheung Tsui , Yidi Wang

In this article, we introduce a new cohomology theory associated to a Lie 2-algebras. This cohomology theory is shown to extend the classical cohomology theory of Lie algebras; in particular, we show that the second cohomology group…

Category Theory · Mathematics 2022-08-25 Camilo Angulo

An algebraic deformation theory of module-algebras over a bialgebra is constructed. The cases of module-coalgebras, comodule-algebras, and comodule-coalgebras are also considered.

Rings and Algebras · Mathematics 2007-05-23 Donald Yau