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We present an overview of the notions of exact sequences of Hopf algebras and tensor categories and their connections. We also present some examples illustrating their main features; these include simple fusion categories and a natural…

Quantum Algebra · Mathematics 2020-03-30 Sonia Natale

In this paper we consider some classical varieties of linear algebras over the field which has characteristic 0. For every considered variety we take a category of the finite generated free algebras of this variety. And for every this…

Rings and Algebras · Mathematics 2012-10-25 A. Tsurkov

We sudy the behaviour of endomorphisms and automorphisms of groups involved in abelian group extensions. The main result can be stated as follows: Let $0\to N\to G\to Q \to 1$ be an abelian group extension. Then one has the following exact…

Group Theory · Mathematics 2015-12-11 Mariam Pirashvili

We construct a theory of the derived PD-Hirsch extension of the log crystalline complex of a log smooth scheme and we construct a fundamental filtered dga $(H_{{\rm zar},{\rm TW}},P)$ and a fundamental filtered complex $(H_{\rm zar},P)$ for…

Algebraic Geometry · Mathematics 2025-03-19 Yukiyoshi Nakkajima

It is shown that if T is a connected nontrivial graph and X is an arbitrary finite simplicial complex, then there is a graph G such that the complex Hom(T,G) is homotopy equivalent to X. The proof is constructive, and uses a nerve lemma.…

Combinatorics · Mathematics 2007-05-23 Anton Dochtermann

We address the question of finding algebraic properties that are respectively equivalent, for a morphism between algebraic varieties over an algebraically closed field of characteristic zero, to be an homeomorphism for the Zariski topology…

Algebraic Geometry · Mathematics 2022-11-16 François Bernard , Goulwen Fichou , Jean-Philippe Monnier , Ronan Quarez

We prove that the canonical ring of a smooth projective variety is finitely generated.

Algebraic Geometry · Mathematics 2008-08-14 Caucher Birkar , Paolo Cascini , Christopher D. Hacon , James McKernan

Let $A$ be a unital simple separable exact C$^*$-algebra which is approximately divisible and of real rank zero. We prove that the set of positive elements in $A$ with a fixed non-compact Cuntz class has vanishing homotopy groups. Combined…

Operator Algebras · Mathematics 2022-10-27 Andrew S. Toms

We prove a structure theorem for the Albanese maps of varieties with Q-linearly trivial log canonical divisors. Our start point is the action of a nonlinear algebraic group on a projective variety.

Algebraic Geometry · Mathematics 2019-01-09 Jinsong Xu

We consider a notion of exact sequences in any -not necessarily exact- pointed category relative to a given (E;M)-factorization structure. We apply this notion to introduce and investigate a new notion of exact sequences of semimodules over…

Category Theory · Mathematics 2011-11-03 Jawad Abuhlail

In this paper we consider some classical varieties of linear algebras over the field which has characteristic 0. For every considered variety we take a category of the finite generated free algebras of this variety. And for every this…

Rings and Algebras · Mathematics 2013-09-26 A. Tsurkov

We introduce normal cores, as well as the more general action cores, in the context of a semi-abelian category, and further generalise those to split extension cores in the context of a homological category. We prove that, if the category…

Category Theory · Mathematics 2023-07-26 D. Bourn , A. S. Cigoli , J. R. A. Gray , T. Van der Linden

We define and provide some basic analysis of various types of crossed products by semimultiplicative sets, and then prove a $KK$-theoretical descent homomorphisms for semimultiplicative sets in accord with the descent homomorphism for…

Operator Algebras · Mathematics 2011-11-18 Bernhard Burgstaller

We study the logarithmic syntomic cohomology of fine and saturated log schemes and its realization in the logarithmic motivic stable homotopy category $\mathrm{logSH}(\mathrm{pt}_\mathbb{N})$ of a log point. We prove that logarithmic…

Algebraic Geometry · Mathematics 2025-12-03 Doosung Park , Paul Arne Østvær

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

Over a monoidal model category, under some mild assumptions, we equip the categories of colored PROPs and their algebras with projective model category structures. A Boardman-Vogt style homotopy invariance result about algebras over…

Algebraic Topology · Mathematics 2009-09-25 Mark W. Johnson , Donald Yau

We show that the fundamental groups of normal complex algebraic varieties share many properties of the fundamental groups of smooth varieties. The jump loci of rank one local systems on a normal variety are related to the jump loci of a…

Algebraic Geometry · Mathematics 2017-08-30 Donu Arapura , Alexandru Dimca , Richard Hain

The author proposes a method for investigating actions of finite groups on aspherical spaces. Complete homotopy classification of free actions of finite groups on aspherical spaces is obtained. Also there are some results about non-free…

General Topology · Mathematics 2010-09-01 Lev Lokutsievskiy

We study some basic properties of schematic homotopy types and the schematization functor. We describe two different algebraic models for schematic homotopy types: co-simplicial Hopf alegbras and equivariant co-simplicial algebras, and…

Algebraic Geometry · Mathematics 2014-01-14 L. Katzarkov , T. Pantev , B. Toen

We describe various path homology theories constructed for a directed hypergraph. We introduce the category of directed hypergraphs and the notion of a homotopy in this category. Also, we investigate the functoriality and the homotopy…

Algebraic Topology · Mathematics 2021-09-22 Yuri Muranov , Anna Szczepkowska , Vladimir Vershinin