On a generalisation of finite $T$-groups

Chi Zhang, Wenbin Guo

Let $\sigma =\{{\sigma }_i|i\in I\}$ is some partition of all primes $\mathbb{P}$ and $G$ a finite group. A subgroup $H$ of $G$ is said to be $\sigma$-subnormal in $G$ if there exists a subgroup cha…