Generation Gaps and Abelianised Defects of Free Products

Karl W. Gruenberg, Peter A. Linnell

Let G be a group of the form G_1* ... *G_n, the free product of n subgroups, and let M be a ZG-module of the form ${⨁}_{i=1}^n{M}_i{\otimes }_{\mathbb{Z}{G}_i}\mathbb{Z}G$. We sh…