The class of locally soluble group is not $N_0$-closed. P.Hall has given an (unpublished) example described in Part 2 of Robinson's "Finiteness Conditions and Generalized Soluble Groups". Theorem 8.19.1 on page 91.
The class of locally soluble group is not $N_0$-closed. P.Hall has given an (unpublished) example described in Part 2 of Robinson's "Finiteness Conditions and Generalized Soluble Groups". Theorem 8.19.1 on page 91.