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We consider two variants of those Abelian groups with all proper characteristic subgroups isomorphic and give an in-depth study of their basic and specific properties in either parallel or contrast to the Abelian groups with all proper…

Rings and Algebras · Mathematics 2023-01-24 Andrey R. Chekhlov , Peter V. Danchev

We give algebraic characterizations of the type I and CCR properties for locally compact second countable, ample Hausdorff groupoids in terms of subquotients of their Boolean inverse semigroups of compact open bisections. It yields in turn…

Operator Algebras · Mathematics 2020-12-16 Gabriel Favre , Sven Raum

We present some results about quasiconvex subgroups of infinite index and their products. After that we extend the standard notion of a subgroup commensurator to an arbitrary subset of a group, and generalize some of the previously known…

Group Theory · Mathematics 2007-05-23 Ashot Minasyan

For a given inverse semigroup, one can associate an \'etale groupoid which is called the universal groupoid. Our motivation is studying the relation between inverse semigroups and associated \'etale groupoids. In this paper, we focus on…

Group Theory · Mathematics 2020-02-10 Fuyuta Komura

Given a locally compact \'etale groupoid and an ideal $I$ in its groupoid C$^*$-algebra, we show that $I$ defines a family of ideals in group C$^*$-algebras of the isotropy groups and then study to which extent $I$ is determined by this…

Operator Algebras · Mathematics 2024-06-03 Johannes Christensen , Sergey Neshveyev

It is well-known that every finite subgroup of GL_d(Q_{\ell}) is conjugate to a subgroup of GL_d(Z_{\ell}). However, this does not remain true if we replace general linear groups by symplectic groups. We say that G is a group of inertia…

Number Theory · Mathematics 2007-05-23 Alice Silverberg , Yuri G. Zarhin

A group G is a cn-group if for each subgroup H of G there exists a normal subgroup N of G such that the index of both H and N in HN is finite. The class of cn-groups contains properly the classes of core- finite groups and that of groups in…

Group Theory · Mathematics 2017-05-09 Carlo Casolo , Ulderico Dardano , Silvana Rinauro

The present work is concerned with characterizing some algebraic invariants of edge ideals of hypergraphs. To this aim, firstly, we introduce some kinds of combinatorial invariants similar to matching numbers for hypergraphs. Then we…

Commutative Algebra · Mathematics 2025-06-10 Somayeh Moradi , Fahimeh Khosh-Ahang Ghasr

In this paper, we introduce the notion of abelian endoregular modules as those modules whose endomorphism rings are abelian von Neumann regular. We characterize an abelian endoregular module $M$ in terms of its $M$-generated submodules. We…

Rings and Algebras · Mathematics 2019-03-12 Mauricio Medina-Bárcenas , Hanna Sim

We provide a correspondence between one-sided coideal subrings and one-sided ideal two-sided coideals in an arbitrary bialgebroid. We prove that, under some expected additional conditions, this correspondence becomes bijective for Hopf…

Rings and Algebras · Mathematics 2023-09-11 Laiachi El Kaoutit , Aryan Ghobadi , Paolo Saracco , Joost Vercruysse

In this paper, we have introduced the notion of (1,2)-ideal in an LA-semigroup and shown that (1,2)-ideal and two-sided ideal coincide in an intra-regular LA-semigroup. We have characterized an intra-regular LA-semigroup by using the…

Group Theory · Mathematics 2010-12-30 Madad Khan , Venus Amjid , Faisal

In this paper we investigate some properties of ideals in group algebras of finite groups over fields. First, we highlight an important link between their dimension, their minimal Hamming distance and the group order. This is a generalized…

Group Theory · Mathematics 2022-02-28 Martino Borello , Wolfgang Willems , Giovanni Zini

The paper investigates a significant part of the automorphic, in fact of the so-called Eisenstein cohomology of split odd orthogonal groups over Q. The main result provides a description of residual and regular Eisenstein cohomology classes…

Number Theory · Mathematics 2011-06-07 G. Gotsbacher , H. Grobner

In this article, we study group theoretical embedding properties of subgroups in central products of finite groups. Specifically, we give characterizations of normal, subnormal, and abnormal subgroups of a central product of two groups.

Group Theory · Mathematics 2014-12-16 Dandrielle Lewis , Ayah Almousa , Eric Elert

We give a categorical description of all abelian varieties with commutative endomorphism ring over a finite field with $q=p^a$ elements in a fixed isogeny class in terms of pairs consisting of a fractional $\mathbb Z[\pi,q/\pi]$-ideal and a…

Number Theory · Mathematics 2025-08-05 Jonas Bergström , Valentijn Karemaker , Stefano Marseglia

We prove that an hypersemigroup $H$ is regular if and only, for any fuzzy subset $f$ of $H$, we have $f\preceq f\circ 1\circ f$ and it is intra-regular if and only if, for any fuzzy subset $f$ of $H$, we have $f\preceq 1\circ f\circ f\circ…

General Mathematics · Mathematics 2016-06-21 Niovi Kehayopulu

For each pointed abelian group $(A,c)$, there is an associated {\em Galkin quandle} $G(A,c)$ which is an algebraic structure defined on $\Bbb Z_3\times A$ that can be used to construct knot invariants. It is known that two finite Galkin…

Combinatorics · Mathematics 2011-08-11 W. Edwin Clark , Xiang-dong Hou

We consider an inclusion $B\subseteq M$ of finite von Neumann algebras satisfying $B'\cap M\subseteq B$. A partial isometry $v\in M$ is called a groupoid normalizer if $vBv^*, v^*Bv\subseteq B$. Given two such inclusions $B_i\subseteq M_i$,…

Operator Algebras · Mathematics 2010-01-22 Junsheng Fang , Roger R. Smith , Stuart A. White , Alan D. Wiggins

In a stable abelian group, we characterize generic types of cosets of type-definable subgroups.

Logic · Mathematics 2007-05-23 Martin Ziegler

We study the topology of the primitive ideal space of groupoid C*-algebras for groupoids with abelian isotropy. Our results include the known results for action groupoids with abelian stabilizers. Furthermore, we obtain complete results…

Operator Algebras · Mathematics 2021-08-26 Daniel W. van Wyk , Dana P. Williams