Manfred Hartl. 
On successive quotients of group ring. 

Abstract : For all groups G and N-series {\cal N} of G a functorial 
description is given for the first three quotients of the
filtration of the integral group ring which is induced by {\cal N}. 
As a key tool {\cal N}-polynomial maps on G are introduced and
studied; an inductive characterization of such maps is given and 
used to identify an important class of nonlinear functions as {\cal
N}-polynomial maps.