Locally nilpotent groups of units in tiled rings. (Q975108)

Let \(R\) be an Artinian local ring with maximal ideal \(\mathfrak m\). Assume that \(R/\mathfrak m\) is commutative and \(\mathfrak m/\mathfrak m^2\) central in \(R/\mathfrak m^2\). For a basic tiled \(R\)-algebra \(\Lambda\), every maximal locally nilpotent subgroup of \(\Lambda^\times\) is a maximal Engel subgroup. The main result describes Engel subgroups of \(\Lambda^\times\) up to conjugacy.