Generalized dimension subgroups and derived functors

Every two-sided ideal $\mathfrak a$ in the integral group ring $\mathbb Z[G]$ of a group $G$ determines a normal subgroup $G \cap (1 + \mathfrak a)$ of $G$. In this paper certain problems related to the identification of such subgroups, and their relationship with derived functors in the sense of Dold-Puppe, are discussed.