Nilpotent Residual of a Finite Group
Let $F$ be a nilpotent group acted on by a group $H$ via automorphisms and let the group $G$ admit the semidirect product $FH$ as a group of automorphisms so that $C_G(F) = 1$. We prove that the order of $γ_\infty(G)$, the rank of $γ_\infty(G)$ are bounded in terms of the orders of $γ_{\infty}(C_G(H))$ and $H$, the rank of $γ_{\infty}(C_G(H))$ and the order of $H$, respectively in cases where either $FH$ is a Frobenius group; $FH$ is a Frobenius-like group satisfying some certain conditions; or $FH=\langle α,β\rangle$ is a dihedral group generated by the involutions $α$ and $β$ with $F =\langle αβ\rangle$ and $H =\langleα\rangle$.
math.GR↗