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We establish a unified group-theoretic framework bridging the arithmetic homotopy exact sequence of a variety and the Birman exact sequence of a surface. Within this framework, we reinterpret classical arithmetic notions - such as the…

Algebraic Geometry · Mathematics 2025-12-24 Miltiadis Karakikes , Sotiris Karanikolopoulos , Aristides Kontogeorgis , Dimitrios Noulas

We introduce the notion of double cosets relative to two fusion subcategories of a fusion category. Given a tensor functor $F : \C \to \D$ between fusion categories, we introduce an equivalence relation $\approx^F$ on the set $\Lambda_\C$…

Quantum Algebra · Mathematics 2013-07-30 S. Burciu , A. Bruguières

For a classical group $G$ over a field $F$ together with a finite-order automorphism $\theta$ that acts compatibly on $F$, we describe the fixed point subgroup of $\theta$ on $G$ and the eigenspaces of $\theta$ on the Lie algebra…

Representation Theory · Mathematics 2019-10-15 Jinwei Yang , Zhiwei Yun

We give a complete characterization of pseudovarieties of semigroups whose finitely generated relatively free profinite semigroups are equidivisible. Besides the pseudovarieties of completely simple semigroups, they are precisely the…

Group Theory · Mathematics 2019-03-18 Jorge Almeida , Alfredo Costa

We show that the functor sending a locally compact Hausdorff space $X$ to the $\infty$-category of spectral sheaves $\mathrm{Shv}(X; \mathrm{Sp})$ is initial among all continuous six-functor formalisms on the category of locally compact…

K-Theory and Homology · Mathematics 2025-08-14 Qingchong Zhu

We consider the quotient of an exact or one-sided exact category $\mathcal{E}$ by a so-called percolating subcategory $\mathcal{A}$. For exact categories, such a quotient is constructed in two steps. Firstly, one localizes $\mathcal{E}$ at…

Category Theory · Mathematics 2020-06-22 Ruben Henrard , Adam-Christiaan van Roosmalen

We define a cohomology for an arbitrary $K$-linear semistrict semigroupal 2-category $(\mathfrak{C},\otimes)$ (called in the paper a Gray semigroup) and show that its first order (unitary) deformations, up to the suitable notion of…

Quantum Algebra · Mathematics 2013-08-13 Josep Elgueta

We define equivariantization of tensor categories under tensor group scheme actions and give necessary and sufficient conditions for an exact sequence of tensor categories to be an equivariantization under a finite group or finite group…

Quantum Algebra · Mathematics 2011-12-15 Alain Bruguières , Sonia Natale

For any abelian compact Lie group $G$, we introduce a family of $G$-stratified pseudomanifolds, whose main feature is the preservation of the orbit spaces in the category of stratified pseudomanifolds. Which generalize a previous definition…

Algebraic Topology · Mathematics 2007-05-23 F. Dalmagro

We study perverse sheaves of categories their connections to classical algebraic geometry. We show how perverse sheaves of categories encode naturally derived categories of coherent sheaves on $\mathbb{P}^1$ bundles, semiorthogonal…

Algebraic Geometry · Mathematics 2019-07-01 Andrew Harder , Ludmil Katzarkov

We apply the technique of S^1-equivariant localization to sheaves on loop spaces in derived algebraic geometry, and obtain a fundamental link between two families of categories at the heart of geometric representation theory. Namely, we…

Representation Theory · Mathematics 2007-06-05 David Ben-Zvi , David Nadler

We study a number of categorical quasi-uniform structures induced by functors. We depart from a category $\mathcal{C}$ with a proper $(\mathcal{E}, \mathcal{M})$-factorization system, then define the continuity of a $\mathcal{C}$-morphism…

Category Theory · Mathematics 2023-02-07 Minani Iragi , David Holgate

On a suitable category of formal schemes equipped with codimension functions we construct a canonical pseudofunctor (-)^# taking values in the corresponding categories of Cousin complexes. Cousin complexes on such a formal scheme X…

Algebraic Geometry · Mathematics 2007-05-23 Joseph Lipman , Suresh Nayak , Pramathanath Sastry

We develop an approach that allows to construct semiorthogonal decompositions of derived categories of surfaces with cyclic quotient singularities whose components are equivalent to derived categories of local finite dimensional algebras.…

Algebraic Geometry · Mathematics 2020-04-09 Joseph Karmazyn , Alexander Kuznetsov , Evgeny Shinder

Category theory is a branch of mathematics that provides a formal framework for understanding the relationship between mathematical structures. To this end, a category not only incorporates the data of the desired objects, but also…

Category Theory · Mathematics 2024-07-26 Niels van der Weide , Nima Rasekh , Benedikt Ahrens , Paige Randall North

The Grothendieck construction is a fundamental link between indexed categories and opfibrations. This work is a detailed study of the Grothendieck construction over a small tight bipermutative category in the context of Cat-enriched…

Category Theory · Mathematics 2024-04-04 Donald Yau

We establish a novel approach to computing $G$-equivariant cohomology for a finite group $G$, and demonstrate it in the case that $G = C_{p^n}$. For any commutative ring spectrum $R$, we prove a symmetric monoidal reconstruction theorem for…

Algebraic Topology · Mathematics 2023-04-03 David Ayala , Aaron Mazel-Gee , Nick Rozenblyum

We develop the deformation-obstruction calculus for morphisms of complexes with a fixed lift of the codomain, to derived categories of flat nilpotent deformations of abelian categories. As an application, we give an alternative proof that…

Algebraic Geometry · Mathematics 2025-11-14 Pieter Belmans , Wendy Lowen , Shinnosuke Okawa , Andrea T. Ricolfi

In this paper, we present a construction from a Reedy category $C$ of a direct category $\operatorname{Down}(C)$ and a functor $\operatorname{Down}(C) \to C$, which exhibits $C$ as an $(\infty,1)$-categorical localization of…

Category Theory · Mathematics 2025-02-10 Genki Sato

Given Gray-categories $P$ and $L$, there is a Gray-category $\mathrm{Tricat}_{\mathrm{ls}}(P,L)$ of locally strict trihomomorphisms with domain $P$ and codomain $L$, tritransformations, trimodifications, and perturbations. If the domain $P$…

Category Theory · Mathematics 2014-08-18 Lukas Buhné