This book is the first to give a comprehensive account of subnormal subgroups of both finite and infinite groups. The authors trace the historical development of the subject from the early work of Wielandt, including the celebrated "join problem," to very recent results relating to the elusive subnormalizer of a subgroup. The book explains how the study of group rings can give a powerful and unified approach to major problems and encourages postgraduates and researchers in group theory and ring theory to further explore problems whose solutions remain incomplete.

The central concept in this monograph is that of a soluble group - a group which is built up from abelian groups by repeatedly forming group extensions. It covers all the major areas, including finitely generated soluble groups, soluble groups of finite rank, modules over group rings, algorithmic problems, applications of cohomology, and finitely presented groups, whilst remaining fairly strictly within the boundaries of soluble group theory. An up-to-date survey of
the area aimed at research students and academic algebraists and group theorists, it is a compendium of information that will be especially useful as a reference work for researchers in the field.