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Zbl 0953.20010
Wang, Yanming
Finite groups with some subgroups of Sylow subgroups $c$-supplemented.
(English)
[J] J. Algebra 224, No. 2, 467-478 (2000). ISSN 0021-8693

The author introduces a generalization of both being complemented'' and his concept of $c$-normality [J. Algebra 180, No. 3, 954-965 (1996; Zbl 0847.20010)] as follows: a subgroup $H$ of a group $G$ is said to be $c$-supplemented (in $G$) if there exists a subgroup $K$ of $G$ such that $G=HK$ and $H\cap K\le\text{core}_G(H)$, the largest normal subgroup of $G$ contained in $H$.\par Theorem 3.1: Let $G$ be a finite group and let $P$ be a Sylow $p$-subgroup of $G$ where $p$ is a prime divisor of $|G|$ with $(|G|,p-1)=1$. Suppose that every maximal subgroup of $P$ is $c$-supplemented in $G$ and any two complements of $P$ in $G$ are conjugate in $G$. Then $G/O_p(G)$ is $p$-nilpotent and every $p'$-subgroup of $G$ is contained in some Hall $p'$-subgroup of $G$. Theorem 3.3: Let $G$ be a finite group and let $N$ be a normal subgroup of $G$ such that $G/N$ is supersoluble. If every maximal subgroup of every Sylow subgroup of $N$ is $c$-supplemented in $G$, then $G$ is supersoluble. Theorem 4.2: Let $G$ be a finite group and let $p$ be the smallest prime divisor of $|G|$. If $G$ is $A_4$-free and every second-maximal subgroup of a Sylow $p$-subgroup of $G$ is $c$-normal in $G$, then $G/O_p(G)$ is $p$-nilpotent. The last two theorems generalize results by {\it A. Ballester-Bolinches} and {\it X. Guo} [Arch. Math. 72, No. 3, 161-166 (1999; Zbl 0929.20015)].
[Hans Lausch (Clayton)]
MSC 2000:
*20D40 Products of subgroups of finite groups
20D20 Sylow subgroups of finite groups
20D35 Subnormal subgroups of finite groups

Keywords: $c$-normality; finite groups; Sylow subgroups; maximal subgroups; complements; Hall subgroups; $c$-supplemented subgroups

Citations: Zbl 0847.20010; Zbl 0929.20015

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