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Given a finite group $G$, we denote by $L(G)$ the subgroup lattice of $G$ and by ${\cal CD}(G)$ the Chermak-Delgado lattice of $G$. In this note, we determine the finite groups $G$ such that $|{\cal CD}(G)|=|L(G)|-k$, $k=1,2$.

Group Theory · Mathematics 2022-09-05 Georgiana Fasolă , Marius Tărnăuceanu

A group $G$ is said to have dense solitary subgroups if each non-empty open interval in its subgroup lattice $L(G)$ contains a solitary subgroup. In this short note, we find all finite groups satisfying this property.

Group Theory · Mathematics 2024-12-13 Marius Tărnăuceanu

In this note we describe the structure of finite groups G whose Chermak-Delgado lattice is the interval [G/Z(G)] = {H \in L(G) \mid Z(G)\leq H\leq G}.

Group Theory · Mathematics 2016-12-12 Marius Tărnăuceanu

For a finite group G, we denote by v(G) the number of conjugacy classes of subgroups of G not in CD(G). In this paper, we determine the finite groups G such that v(G)=1,2,3.

Group Theory · Mathematics 2025-04-22 Jiakuan Lu , Xi Huang , Qinwei Lian , Wei Meng

A group $G$ is said to have dense normalizers if each non-empty open interval in its subgroup lattice $L(G)$ contains the normalizer of a certain subgroup of $G$. In this note, we find all finite groups satisfying this property. We also…

Group Theory · Mathematics 2025-04-01 Marius Tărnăuceanu

Given a finite group $G$, we denote by $L(G)$ the subgroup lattice of $G$ and by ${\rm Isolated}(G)$ the set of isolated subgroups of $G$. In this note, we describe finite groups $G$ such that $|{\rm Isolated}(G)|=|L(G)|-k$, where…

Group Theory · Mathematics 2021-11-30 Marius Tărnăuceanu

The Chermak-Delgado lattice of a finite group is a modular, self-dual sublattice of the lattice of subgroups of $G$. The least element of the Chermak-Delgado lattice of $G$ is known as the Chermak-Delgado subgroup of $G$. This paper…

Group Theory · Mathematics 2022-07-06 Ryan McCulloch

The Chermak-Delgado lattice of a finite group G is a self-dual sublattice of the subgroup lattice of G. In this paper, we determine finite p-groups with at most p2 + p subgroups not in Chermak-Delgado lattice.

Group Theory · Mathematics 2023-07-27 Guojie Liu , Haipeng Qu , Lijian An

For a finite group G with subgroup H the Chermak-Delgado measure of H in G refer to the product of the order of H with the order of its centralizer, C_G(H). The set of all subgroups with maximal Chermak-Delgado measure form a sublattice,…

Group Theory · Mathematics 2014-07-24 Ben Brewster , Peter Hauck , Elizabeth Wilcox

Let $G$ be a finite group and $H\leq G$. The Chermak-Delgado measure of $H$ is defined as the number $|H|\cdot|C_{G}(H)|$. In this paper, we identify finite groups that exhibit the maximum number of Chermak-Delgado measures under some…

Group Theory · Mathematics 2025-04-08 Guojie Liu , Haipeng Qu , Lijian An

It is an open question in the study of Chermak-Delgado lattices precisely which finite groups $G$ have the property that $CD(G)$ is a chain of length $0$. In this note, we determine two classes of groups with this property. We prove that if…

Group Theory · Mathematics 2018-01-23 Ryan McCulloch , Marius Tărnăuceanu

The Chermak-Delgado lattice of a finite group $G$ is a self-dual sublattice of the subgroup lattice of $G$. In this paper, we focus on finite groups whose Chermak-Delgado lattice is a subgroup lattice of an elementary abelian $p$-group. We…

Group Theory · Mathematics 2021-07-08 Lijian An

Let G be a finite group and let H be a subgroup of G. The Chermak-Delgado measure of H with respect to G is the product of the order of H with the order of the centralizer of H. Originally described by A. Chermak and A. Delgado, the…

Group Theory · Mathematics 2014-07-24 Ben Brewster , Elizabeth Wilcox

We investigate the question of how many subgroups of a finite group are not in its Chermak-Delgado lattice. The Chermak-Delgado lattice for a finite group is a self-dual lattice of subgroups with many intriguing properties. Fasol\u{a} and…

Group Theory · Mathematics 2024-08-02 David Burrell , William Cocke , Ryan McCulloch

In this short note, we describe finite groups all of whose non-trivial cyclic subgroups have the same Chermak-Delgado measure.

Group Theory · Mathematics 2024-09-02 Marius Tărnăuceanu

The Chermak-Delgado lattice of a finite group is a dual, modular sublattice of the subgroup lattice of the group. This paper considers groups with a quasi-antichain interval in the Chermak-Delgado lattice, ultimately proving that if there…

Group Theory · Mathematics 2014-07-24 Ben Brewster , Peter Hauck , Elizabeth Wilcox

Let $G$ be an infinite compact group. We prove that for every cardinal $\kappa$ between the density and the weight of $G$, there exists a dense subgroup of $G$ of density $\kappa$.

Group Theory · Mathematics 2025-07-28 Dekui Peng

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

Let $G$ be a finite group, define $I(G)=\{x\in G : x^{2}=1\}$, $C(G)=$ set of the cyclic subgroups of $G$, $i(G)=|I(G)|$ and $c(G)=|C(G)|$. In this article, we will classify finite groups with $i(G)=c(G)-r$ for $r=0,1,$ and $2$. We also…

Group Theory · Mathematics 2025-09-16 Vaibhav Chhajer , Palash Sharma

It is proven that if $G$ is a finite group, then $G^\omega$ has $2^{\mathfrak c}$ dense nonmeasurable subgroups. Also, other examples of compact groups with dense nonmeasurable subgroups are presented.

General Topology · Mathematics 2014-07-04 F. Javier Trigos-Arrieta
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