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We propose the notion of the {\em crystalline sub-representation functor} defined on $p$-adic representations of the Galois groups of finite extensions of $\Qp$, with certain restrictions in the case of integral representations. By studying…

Algebraic Geometry · Mathematics 2007-05-23 Minhyong Kim , Susan Marshall

We introduce a formalism for derived moduli functors on differential graded associative algebras, which leads to non-commutative enhancements of derived moduli stacks and naturally gives rise to structures such as Hall algebras. Descent…

Algebraic Geometry · Mathematics 2020-08-27 J. P. Pridham

We instal homological algebra, including derived functors, on certain non-additive categories like categories of pointed CW-complexes, modules of monoids or sheaves thereof. We apply this theory to Monoid schemes and sheaves on them,…

Number Theory · Mathematics 2017-09-04 Anton Deitmar

In this paper, we first introduce stable functors with respect to a preenveloping/precovering subcategory and investigate some of their properties. Using that we then introduce and study a relative complete cohomology theory in abelian…

Rings and Algebras · Mathematics 2023-10-06 Shoutao Guo , Li Liang

We develop a theory of `non-abelian higher special elements' in the non-commutative exterior powers of the Galois cohomology of $p$-adic representations. We explore their relation to the theory of organising matrices and thus to the Galois…

Number Theory · Mathematics 2022-01-20 Daniel Macias Castillo , Kwok-Wing Tsoi

The Chern-Galois theory is developed for corings or coalgebras over non-commutative rings. As the first step the notion of an entwined extension as an extension of algebras within a bijective entwining structure over a non-commutative ring…

Rings and Algebras · Mathematics 2008-11-01 Gabriella Böhm , Tomasz Brzezinski

In this paper, we introduce the notions of crossed module of associative conformal algebras, 2-term strongly homotopy associative conformal algebras, and discuss the relationship between them and the 3-th Hochschild cohomology of…

Quantum Algebra · Mathematics 2022-11-22 Bo Hou , Jun Zhao

Expansions of abelian categories are introduced. These are certain functors between abelian categories and provide a tool for induction/reduction arguments. Expansions arise naturally in the study of coherent sheaves on weighted projective…

Representation Theory · Mathematics 2010-09-20 Xiao-Wu Chen , Henning Krause

In this paper, for given an algebraic theory $T$ whose category $C$ of models is semi-abelian, we consider the topological models of $T$ called topological $T$-algebras and obtain some results related to the fundamental groups of…

Category Theory · Mathematics 2018-01-29 Osman Mucuk , Serap Demir

We extend some classical constructions in commutative algebra to the setting of modules over orders in (non-commutative) semisimple algebras. Our theory incorporates, inter alia, `reduced' versions of the notions of higher Fitting…

Number Theory · Mathematics 2025-09-16 David Burns , Takamichi Sano

The regular subgroup determining an induced Hopf Galois structure for a Galois extension $L/K$ is obtained as the direct product of the corresponding regular groups of the inducing subextensions. We describe here the associated Hopf algebra…

Number Theory · Mathematics 2022-02-22 Daniel Gil-Muñoz , Anna Rio

Torsion theories play an important role in abelian categories and they have been widely studied in the last sixty years. In recent years, with the introduction of pretorsion theories, the definition has been extended to general…

Category Theory · Mathematics 2024-07-17 Federico Campanini , Francesca Fedele

We define a Galois structure on the category of pairs of equivalence relations in an exact Mal'tsev category, and characterize central and double central extensions in terms of higher commutator conditions. These results generalize both the…

Category Theory · Mathematics 2018-09-28 Arnaud Duvieusart , Marino Gran

The purpose of this article is to prove that the category of cocommutative Hopf $K$-algebras, over a field $K$ of characteristic zero, is a semi-abelian category. Moreover, we show that this category is action representable, and that it…

Category Theory · Mathematics 2015-05-05 Marino Gran , Gabriel Kadjo , Joost Vercruysse

Hopf Galois theory expands the classical Galois theory by considering the Galois property in terms of the action of the group algebra k[G] on K/k and then replacing it by the action of a Hopf algebra. We review the case of separable…

Group Theory · Mathematics 2017-04-18 Teresa Crespo , Anna Rio , Montserrat Vela

We outline the theory of reflections for prederivators, derivators and stable derivators. In order to parallel the classical theory valid for categories, we outline how reflections can be equivalently described as categories of fractions,…

Category Theory · Mathematics 2018-02-23 Fosco Loregian

We define a notion on preadditive categories which plays a role similar to the notion of a Grothendieck pretopology on an unenriched category. Each such additive pretopology defines an additive Grothendieck topology and suffices to define…

Category Theory · Mathematics 2022-10-18 Kevin Coulembier

We study the push-forward of Hopf--Galois extensions as the algebraic counterpart of the pullback of principal bundles. We apply the theory of twisted tensor product algebras to endow covariant extensions of modules along a map $\mathsf{F}$…

Quantum Algebra · Mathematics 2025-12-24 Giovanni Landi , Chiara Pagani

Given a monoidal adjunction, we show that the right adjoint induces a braided lax monoidal functor between the corresponding Drinfeld centers provided that certain natural transformations, called projection formula morphisms, are…

Category Theory · Mathematics 2024-02-16 Johannes Flake , Robert Laugwitz , Sebastian Posur

The aim of this paper is to introduce and to investigate the analogues of torsors for compact quantum groups and to study their role in representation theory. Let A be a unitarizable Hopf *-algebra: we show that there is a category…

Quantum Algebra · Mathematics 2007-05-23 Julien Bichon