Abstract:
Throughout the article, all groups are finite. We say that a subgroup $A$ of $G$ is $\pi$-quasinormal in $G$, if $A$ is $1 \pi$-subnormal and modular in $G$. We prove that if the group $G$ is $\pi _{0}$-solvable, where $\pi _{0}=\pi (D) $ and $D$ is the $\pi $-special residual of $G$, and $\pi$-quasi-normality is a transitive relation in $G$, then $D$ is an abelian Hall subgroup of odd order in $G$.