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Related papers: On Some Versions of Hopficity for Abelian Groups

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This paper targets to generalize the notion of Hopfian groups in the commutative case by defining the so-called {\bf relatively Hopfian groups} and {\bf weakly Hopfian groups}, and establishing some their crucial properties and…

Group Theory · Mathematics 2024-08-09 Andrey R. Chekhlov , Peter V. Danchev , Brendan Goldsmith , Patrick W. Keef

We introduce a new class of Abelian groups which lies strictly between the classes of co-Hopfian groups and Dedekind-finite groups, calling these groups {\it Bassian-finite}. We prove the surprising fact that in the torsion case the…

Group Theory · Mathematics 2025-07-16 Peter V. Danchev , Patrick W. Keef

The classes of abelian groups that are (uniformly) strongly Hopfian abelian groups, and dually, (uniformly) strongly co-Hopfian abelian groups have been studied by several authors, including Abdelalim (2015) and Abdelalim-Chillali-Essanouni…

Group Theory · Mathematics 2026-05-29 Peter V. Danchev , Patrick W. Keef

By defining the classes of generalized co-Hopfian and relatively co-Hopfian groups, respectively, we consider two expanded versions of the generalized co-Bassian groups and of the classical co-Hopfian groups giving a close relationship with…

Group Theory · Mathematics 2025-01-22 Andrey R. Chekhlov , Peter V. Danchev , Patrick W. Keef

In our previous paper, we gave a complete list of the finite non-abelian simple groups whose holomorph contains a solvable regular subgroup. In this paper, we refine our previous work by considering all finite almost simple groups. In…

Group Theory · Mathematics 2024-03-25 Cindy Tsang

Continuing recent studies of both the hereditary and super properties of certain classes of Abelian groups, we explore in-depth what is the situation in the quite large class consisting of directly finite Abelian groups. Trying to connect…

Group Theory · Mathematics 2025-03-17 Peter Danchev , Brendan Goldsmith , Fatemeh Karimi

We consider the so-called {\it strongly co-Hopfian} and {\it uniformly strongly co-Hopfian} Abelian groups, significantly generalizing some important results due to Abdelalim in the J. Math. Analysis (2015). Specifically, we prove that any…

Group Theory · Mathematics 2025-12-01 Andrey R. Chekhlov , Peter V. Danchev , Patrick W. Keef

Hopf braces have been introduced as a Hopf-theoretic generalization of skew braces. Under the assumption of cocommutativity, these algebraic structures are equivalent to matched pairs of actions on Hopf algebras, that can be used to produce…

Rings and Algebras · Mathematics 2025-05-14 Marino Gran , Andrea Sciandra

Trying to finalize in some way the present subject, this paper targets to generalize substantially the notions of Bassian and co-Bassian groups by introducing the so-called finitely (co-)Bassian groups, semi (co-)Bassian groups, fully…

Group Theory · Mathematics 2024-03-14 Andrey R. Chekhlov , Peter V. Danchev , Patrick W. Keef

A connection between the Galois-theoretic approach to semi-abelian homology and the homological closure operators is established. In particular, a generalised Hopf formula for homology is obtained, allowing the choice of a new kind of…

Category Theory · Mathematics 2014-10-14 Mathieu Duckerts-Antoine , Tomas Everaert , Marino Gran

By providing a suitable generalization of Newman's bijective correspondence known for cocommutative Hopf algebras, we prove that the category of cocommutative Hopf monoids in any abelian symmetric monoidal category is semi-abelian, once…

Category Theory · Mathematics 2026-03-24 Andrea Sciandra , Zhenbang Zuo

Relying on the techniques and ideas from our recent paper [13], we prove several anti-classification results for various rigidity conditions in countable abelian and nilpotent groups. We prove three main theorems: (1) the rigid abelian…

Logic · Mathematics 2023-12-06 Gianluca Paolini , Saharon Shelah

A group $\Gamma$ is defined to be cofinitely Hopfian if every homomorphism $\Gamma\to\Gamma$ whose image is of finite index is an automorphism. Geometrically significant groups enjoying this property include certain relatively hyperbolic…

Group Theory · Mathematics 2010-12-09 Martin R. Bridson , Daniel Groves , Jonathan A. Hillman , Gaven J. Martin

We completely characterize by finding necessary and sufficient conditions those co-Bassian and generalized co-Bassian Abelian groups having, respectively, the hereditary or the super property, thus giving a new insight in the full discovery…

Group Theory · Mathematics 2025-04-08 Peter V. Danchev , Brendan Goldsmith , Patrick W. Keef

Akbarov's theory of holomorphic reflexivity for topological Hopf algebras has been developed in two directions, namely, by the complication of definitions when expanding the scope and by their simplification when restricting. In the…

Rings and Algebras · Mathematics 2023-01-31 Oleg Aristov

This is a survey on the state-of-the-art of the classification of finite-dimensional complex Hopf algebras. This general question is addressed through the consideration of different classes of such Hopf algebras. Pointed Hopf algebras…

Quantum Algebra · Mathematics 2014-04-01 Nicolás Andruskiewitsch

In this paper we study categorical properties of the category of abelian hypergroups that leads to the notion of hyper (almost) preadditive and hyper (almost) abelian categories. Our goal is to create a path towards a general theory of…

Category Theory · Mathematics 2025-09-11 Kaique Matias de Andrade Roberto , Ana Luiza Tenório

We study the notion of fundamental group in the framework of descent-exact homological categories. This setting is sufficiently wide to include several categories of "algebraic" nature such as the almost abelian categories, the semi-abelian…

Category Theory · Mathematics 2016-04-13 Mathieu Duckerts-Antoine

The adjunction between coalgebras and Hopf algebras, first described by Takeuchi, allows one to prove that the semi-abelian category of cocommutative Hopf algebras has enough $\mathcal E$-projective objects with respect to the class…

Category Theory · Mathematics 2025-09-15 Marino Gran , Andrea Sciandra

By a recent work of Gran-Kadjo-Vercruysse, the category of cocommutative Hopf algebras over a field of characteristic zero is semi-abelian. In this paper, we explore some properties of this categoy, in particular we show that its abelian…

Category Theory · Mathematics 2015-03-25 Christine Vespa , Marc Wambst
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