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JOURNALS // Sibirskii Matematicheskii Zhurnal // Archive

Sibirsk. Mat. Zh., 2009 Volume 50, Number 3, Pages 587–595 (Mi smj1983)

This article is cited in 15 papers

A note on a result of Skiba

Ya. Lia, Sh. Qiaob, Ya. Wangb

a Dept. of Math., Guangdong Institute of Education, Guangzhou, China
b Zhongshan University, Guangzhou, China

Abstract: A subgroup $H$ of a group $G$ is called weakly $s$-permutable in $G$ if there is a subnormal subgroup $T$ of $G$ such that $G=HT$ and $H\cap T\le H_{sG}$, where $H_{sG}$ is the maximal $s$-permutable subgroup of $G$ contained in $H$. We improve a nice result of Skiba to get the following
Theorem. Let $\mathscr F$ be a saturated formation containing the class of all supersoluble groups $\mathscr U$ and let $G$ be a group with $E$ a normal subgroup of $G$ such that $G/E\in\mathscr F$. Suppose that each noncyclic Sylow $p$-subgroup $P$ of $F^*(E)$ has a subgroup $D$ such that $1<|D|<|P|$ and all subgroups $H$ of $P$ with order $|H|=|D|$ are weakly $s$-permutable in $G$ for all $p\in\pi(F^*(E))$; moreover, we suppose that every cyclic subgroup of $P$ of order 4 is weakly $s$-permutable in $G$ if $P$ is a nonabelian 2-group and $|D|=2$. Then $G\in\mathscr F$.

Keywords: weakly $s$-permutable subgroup, generalized Fitting subgroup, $p$-nilpotent group, saturated formation.

UDC: 512.54

Received: 10.11.2007


 English version:
Siberian Mathematical Journal, 2009, 50:3, 467–473

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© Steklov Math. Inst. of RAS, 2024