London Mathematical Society Lecture Note Series. 210. Cambridge: Univ. Press,. ix, 130 p. £ 17.95; $ 29.95 (1995).
The aim of these Lecture Notes, considered by the author as a toolkit for operator algebraists, is to provide students and non specialists mathematicians, for the first time, a very clear and unified exposition of the main techniques and results that have shown themselves to be useful in a variety of contents in modern -algebra theory and some of its major applications. These techniques and results centre round the concept of Hilbert -module, an object like Hilbert space provided that the inner product takes its value in a general -algebra instead of being complex-valued. Hilbert -modules first appeared in the work of I. Kaplansky in 1953 on modules over operator algebras. The book is divided in ten chapters and contains a very selective list of references.
The first three chapters present basic definitions and concepts and the elementary theory of Hilbert -modules in the model of classical Hilbert spaces. Chapter 4 presents tensor products. Chapter 5 is a treatment on completely-positive mappings between -algebras and then in the context of Hilbert -algebras. In the chapter 6, a universal positive response is given, under some countability condition on modules, to the following general question: Given a -algebra , can we hope to classify all Hilbert--modules up to unitary equivalence?
Broadly, chapters 4 to 6 are motivated by applications of Hilbert -modules to the -theory and -theory. Chapter 7 is a short interlude on the topic of Morita equivalence, chapter 8 on slice maps and bialgebras, chapter 9 on unbounded operators and chapter 10 on the bounded transform and unbounded multipliers, are oriented towards application to -algebraic quantum group theory, but quantum groups as such do not figure in this book.