Introduction to l2-invariants

This book introduces the reader to the most important concepts and problems in the field of ℓ²-invariants. After some foundational material on group von Neumann algebras, ℓ²-Betti numbers are defined and their use is illustrated by several examples. The text continues with Atiyah''s question on possible values of ℓ²-Betti numbers and the relation to Kaplansky''s zero divisor conjecture. The genera...