Finite groups with generalized $\sigma$-subnormal and $\sigma$-permutable subgroups

N. M. Adarchenko ; A. N. Skiba

Problemy fiziki, matematiki i tehniki, no. 1 (2020), pp. 65-73

Résumé

Throughout this paper, all groups are finite and $G$ always denotes a finite group. We say that a subgroup $H$ of $G$ is nearly modular in $G$ if either $A$ is normal in $G$ or $H_g\ne H^G$ and every chief factor $H/K$ of $G$ between $H_G$ and $H^G$ is nearly central in $G$, that is, $|H/K||GC_G(H/K)|$ divides $pq$ for some primes $p$ and $q$. We say that a subgroup $A$ of $G$ is: (i) nearly $\sigma$-subnormal in $G$ if $A=\langle L,T\rangle$, where $L$ is a nearly modular subgroup and $T$ is a $\sigma$-subnormal subgroup of $G$; (ii) nearly $\sigma$-permutable in $G$ if $A=\langle L,T\rangle$, where $L$ is a nearly modular subgroup and $T$ is a $\sigma$-permutable subgroup of $G$. (iii) weakly $\sigma$-permutable in $G$ if there are a nearly $\sigma$-permutable subgroup $S$ and a subgroup $T$ of $G$ such that $G=HT$ and $H\cap T\leqslant S\leqslant H$. In the given paper, we study finite groups with some systems of nearly $\sigma$-subnormal, nearly $\sigma$-permutable and weakly $\sigma$-permutable subgroups. Some known results are generalized.

Détail

Keywords: finite group, $n$-maximal subgroup, nearly $\sigma$-subnormal subgroup, nearly $\sigma$-permutable subgroup, $\sigma$-nearly nilpotent group.