This book highlights important developments on artinian modules over
group rings of generalized nilpotent groups. Along with traditional
topics such as direct decompositions of artinian modules, criteria of
complementability for some important modules, and criteria of
semisimplicity of artinian modules, it also focuses on recent advanced
results on these matters. The theory of modules over groups has its own
specific character that plays an imperative role here and, for example,
allows a significant generalization of the classical Maschke Theorem on
some classes of infinite groups. Conversely, it leads to establishing
direct decompositions of artinian modules related to important natural
formations, which, in turn, find very efficient applications in infinite
groups.