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The main purpose of this paper is to give a new definition for the notion of group-groupoid. Also, several basic properties of group-groupoids are established.

Group Theory · Mathematics 2015-12-31 Mihai Ivan

Following Hopkins and Singer, we give a definition for the differential equivariant K-theory of a smooth manifold acted upon by a finite group. The ring structure for differential equivariant K-theory is developed explicitly. We also…

Algebraic Topology · Mathematics 2009-06-01 Michael L. Ortiz

We define k-genericity and k-largeness for a subset of a group, and determine the value of k for which a k-large subset of G^n is already the whole of G^n , for various equationally defined subsets. We link this with the inner measure of…

Logic · Mathematics 2020-03-09 Khaled Jaber , Frank Olaf Wagner

In this note we give some new results concerning the subgroup commutativity degree of a finite group $G$. These are obtained by considering the minimum of subgroup commutativity degrees of all sections of $G$.

Group Theory · Mathematics 2018-02-13 Marius Tărnăuceanu

By imposing conditions upon the index of a self-centralizing subgroup of a group, and upon the index of the center of the group, we are able to classify the Chermak-Delgado lattice of the group. This is our main result. We use this result…

Group Theory · Mathematics 2025-03-18 Ryan McCulloch , Marius Tărnăuceanu

The aim of this paper is to study the group of isomorphism classes of torsors of finite flat group schemes of rank 2 over a commutative ring $R$. This, in particular, generalises the group of quadratic algebras (free or projective), which…

Algebraic Geometry · Mathematics 2019-02-20 Ilia Pirashvili

This paper is a follow-up to our joint paper with I. Agol, P. Storm and K. Whyte "Finiteness of arithmetic hyperbolic reflection groups". The main purpose is to investigate the effective side of the method developed there and its possible…

Geometric Topology · Mathematics 2011-03-16 Mikhail Belolipetsky

The dead-end depth of an element g of a group with finite generating set A is the distance from g to the complement of the radius d(1,g) closed ball, in the word metric d associated to A. We exhibit a finitely presented group K with two…

Group Theory · Mathematics 2010-08-12 Tim R. Riley , Andrew D. Warshall

A new notion of independence relation is given and associated to it, the class of flat theories, a subclass of strong stable theories including the superstable ones is introduced. More precisely, after introducing this independence…

Logic · Mathematics 2018-04-18 Daniel Palacín , Saharon Shelah

A countable group is residually finite if every nontrivial element can act nontrivially on a finite set. When a group fails to be residually finite, we might want to measure how drastically it fails - it could be that only finitely many…

Group Theory · Mathematics 2024-01-11 Nic Brody , Kasia Jankiewicz

The power graph of a group is the graph whose vertex set is the set of non-trivial elements of group, two elements being adjacent if one is a power of the other. We define a new power graph and study on connectivity, diameter and clique…

Group Theory · Mathematics 2015-01-14 S. H. Jafari

This paper investigates the critical group of a faithful representation of a finite group. It computes the order of the critical group in terms of the character values, and gives some restrictions on its subgroup structure. It also computes…

Combinatorics · Mathematics 2016-10-14 Christian Gaetz

We present the fundamental properties of the K-theory groups of complex vector bundles endowed with actions of magnetic groups. In this work we show that the magnetic equivariant K-theory groups define an equivariant cohomology theory, we…

K-Theory and Homology · Mathematics 2025-05-09 Higinio Serrano , Bernardo Uribe , Miguel A. Xicoténcatl

We show that the subgroup of the Picard group of a $p$-block of a finite group given by bimodules with endopermutation sources modulo the automorphism group of a source algebra is determined locally in terms of the fusion system on a defect…

Representation Theory · Mathematics 2018-05-24 Robert Boltje , Radha Kessar , Markus Linckelmann

Irregular conformal block is an important tool to study a new type of conformal theories, which can be constructed as the colliding limit of the regular conformal block. The irregular conformal block is realized as the $\beta$-deformed…

High Energy Physics - Theory · Physics 2015-06-18 Sang-Kwan Choi , Chaiho Rim

We introduce the new notion of quotient-saturation as a measure of the immensity of the quotient structure of a group. We present a sufficient condition for a finitely presented group to be quotient-saturated, and use it to deduce that…

Group Theory · Mathematics 2024-04-05 Jordi Delgado , Mallika Roy , Enric Ventura

A combinatorial block design $D$ is called $3$-pyramidal if there exists a subgroup $G$ of $\mbox{Aut}(D)$ fixing $3$ points and acting regularly on the other points. If this happens, we say that the design is $3$-pyramidal under $G$. In…

Group Theory · Mathematics 2023-02-28 Xiaofang Gao , Martino Garonzi

In this paper we study the subcategory of finite-length objects of the category of positive level integrable representations of a toroidal Lie algebra. The main goal is to characterize the blocks of the category. In the cases when the…

Representation Theory · Mathematics 2018-07-23 Tanusree Khandai

Let $G$ be a finite group and let $\pi(G)=\{p_1, p_2, \ldots, p_k\}$ be the set of prime divisors of $|G|$ for which $p_1<p_2<\cdots<p_k$. The Gruenberg-Kegel graph of $G$, denoted ${\rm GK}(G)$, is defined as follows: its vertex set is…

Group Theory · Mathematics 2017-05-16 A. Mohammadzadeh , A. R. Moghaddamfar

A recurring theme in finite group theory is understanding how the structure of a finite group is determined by the arithmetic properties of group invariants. There are results in the literature determining the structure of finite groups…

Group Theory · Mathematics 2025-04-04 Christopher A. Schroeder , Hung P. Tong-Viet