Introduction to Lambda Trees

The theory of Λ-trees has its origin in the work of Lyndon on length functions in groups. The first definition of an R-tree was given by Tits in 1977. The importance of Λ-trees was established by Morgan and Shalen, who showed how to compactify a generalisation of Teichmüller space for a finitely generated group using R-trees. In that work they were led to define the idea of a Λ-tree, where Λ is an arbitrary ordered abelian group. Since then there has been much progress in understanding the structure of groups acting on R-trees, notably Rips' theorem on free actions. There has also been some progress for certain other ordered abelian groups Λ, including some interesting connections with model theory.Introduction to Λ-Trees will prove to be useful for mathematicians and research students in algebra and topology.

This book is accessible for beginning research students. Proofs are very detailed and recalled in detail. -- Mathematical Reviews, 2003