On $\tau$-closed $n$-multiply $\sigma$-local formations of finite groups
Group Theory
2021-05-04 v1
Abstract
All groups under consideration are finite. Let σ={σi∣i∈I} be some partition of the set of P, G be a group, and F be a class of groups. Then σ(G)={σi∣σi∩π(G)=∅} and σ(F)=∪G∈Fσ(G). A function f of the form f:σ→{formations of groups} is called a formation σ-function. For any formation σ-function f the class LFσ(f) is defined as follows: LFσ(f)=(G is a group ∣G=1 or G=1 and G/Oσi′,σi(G)∈f(σi) for all σi∈σ(G)). If for some formation σ-function f we have F=LFσ(f), then F is called σ-local, f is called a σ-local definition of F. Every formation is called 0-multiply σ-local. For n>0, a formation F is called n-multiply σ-local provided either F=(1) or F=LFσ(f), where f(σi) is (n−1)-multiply σ-local for all σi∈σ(F). Let τ(G) be a set of subgroups of G such that G∈τ(G). Then τ is called a subgroup functor if for every epimorphism φ : A→ B and any groups H∈τ(A) and T∈τ(B) we have Hφ∈τ(B) and Tφ−1∈τ(A). A class F is called τ-closed if τ(G)⊆F for all G∈F. We describe some properties of τ-closed n-multiply σ-local formations, as well as we prove that the set lσnτ of all τ-closed n-multiply σ-local formations forms a complete modular algebraic lattice. In addition, we proof that lσnτ is σ-inductive and G-separable.
Cite
@article{arxiv.2105.00430,
title = {On $\tau$-closed $n$-multiply $\sigma$-local formations of finite groups},
author = {Inna N. Safonova},
journal= {arXiv preprint arXiv:2105.00430},
year = {2021}
}