A note on meta and para-$\mathfrak{Nil}$-Hamiltonian groups_v3
Hamid Mousavi
TL;DR
The paper investigates finiteness properties of meta-$\mathfrak{Nil}$-Hamiltonian and para-$\mathfrak{Nil}$-Hamiltonian groups under the presence of a soluble subgroup of finite index or a finite-order non-nilpotent subgroup. It introduces and leverages the notion of $\mathcal{W}$-groups, proving that soluble-by-finite meta-$\mathfrak{Nil}$-Hamiltonian groups have finitely generated non-nilpotent subgroups with finite non-nilpotent images, and that many insoluble cases force finiteness or highly constrained structures. It further establishes that para-$\mathfrak{Nil}$-Hamiltonian groups with finite insoluble content are finite, and that when nilpotent subgroups have finite index, the group is polycyclic with a nilpotent $\mathrm{Fit}(G)$ of finite index; in certain finite quotients these groups reduce to well-known small simple groups like $A_5$ or $\mathrm{SL}(2,5)$. The results unify and extend prior work, offering a framework for solvability, polycyclicity, and finiteness classifications within meta- and para-$\mathfrak{Nil}$-Hamiltonian groups.
Abstract
Let $\mathfrak{Nil}$ be the class of nilpotent groups. This article explores the finiteness of meta and para-$\mathfrak{Nil}$-Hamiltonian groups or their derived subgroups when these groups contain a soluble subgroup of finite index or a non-nilpotent (or insoluble) subgroup of finite order respectively.
