We describe finite groups which contain just one conjugate class of self-normalizing subgroups.

We prove that are primitive the finite groups whose normalizers of the Sylow subgroups are primitive. We classify the groups of such class, denoted by $N\mathcal{P}$, and we study the Schunck classes whose boundary is contained in $N\mathcal{P}$. We give also necessary and sufficient conditions in order that the projectors be subnormally embedded.

Let $G$ be a finite group, $p$ the smallest prime dividing the order of $G$ and $P$ a Sylow $p$-subgroup of $G$ with the smallest generator number $d$. There is a set ${ℳ}_d\left(P\right)=\{P_1,P_2,\cdots ,P_d\}$ of maximal subgroups of $P$ such that ${\bigcap }_{i=1}^d{P}_i=\Phi \left(P\right)$. In the present paper, we investigate the structure of a finite group under the assumption that every member of ${ℳ}_d\left(P\right)$ is either $s$-permutably embedded or weakly $s$-permutable in $G$ to give criteria for a group to be $p$-supersolvable or $p$-nilpotent.

A subgroup $H$ of a finite group $G$ is said to be SS-supplemented in $G$ if there exists a subgroup $K$ of $G$ such that $G=HK$ and $H\cap K$ is S-quasinormal in $K$. We analyze how certain properties of SS-supplemented subgroups influence the structure of finite groups. Our results improve and generalize several recent results.

Suppose G is a finite group and H is a subgroup of G. H is called weakly s-permutably embedded in G if there are a subnormal subgroup T of G and an s-permutably embedded subgroup $H_{se}$ of G contained in H such that G = HT and $H\cap T\le H_{se}$; H is called weakly s-supplemented in G if there is a subgroup T of G such that G = HT and $H\cap T\le H_{sG}$, where $H_{sG}$ is the subgroup of H generated by all those subgroups of H which are s-permutable in G. We investigate the influence of the existence of s-permutably embedded and weakly s-supplemented...

Suppose that $G$ is a finite group and $H$ is a subgroup of $G$. Subgroup $H$ is said to be weakly $ℳ$-supplemented in $G$ if there exists a subgroup $B$ of $G$ such that (1) $G=HB$, and (2) if $H_1/H_G$ is a maximal subgroup of $H/H_G$, then $H_{1}B=B{H}_1<G$, where $H_G$ is the largest normal subgroup of $G$ contained in $H$. We fix in every noncyclic Sylow subgroup $P$ of $G$ a subgroup $D$ satisfying $1<\left|D\right|<\left|P\right|$ and study the $p$-nilpotency of $G$ under the assumption that every subgroup $H$ of $P$ with $\left|H\right|=\left|D\right|$ is weakly $ℳ$-supplemented in $G$. Some recent results are generalized.