Wall's finiteness obstruction

The purpose of this note is to give a self contained description of Walls finiteness obstruction

Topological Equivalence of Linear Representations for Cyclic Groups, I & II

In the two parts of this paper we solve a problem of De Rham, proving that Reidemeister torsion invariants determine topological equivalence of linear G-representations, for G a finite cyclic group. Methods in controlled K-theory and surgery theory are developed to establish, and effectively calculate, a necessary and sufficient condition for non-linear similarity in terms of the vanishing of certain non-compact transfer maps. For cyclic groups of 2-power order, we obtain a complete classification of non-linear similarities.Comment: The first version of this paper appeared as MPI Preprint 1997-58, Max Planck Institut fuer Mathematik, Bonn. The final version includes many improvements in exposition and new results. It is now divided into two parts. Part I (36 pages) will appear in Annals of Mathematics, and Part II (43 pages) will appear in Forum Mat

Stability in controlled L-theory

We prove a squeezing/stability theorem for delta-epsilon controlled L-groups when the control map is a fibration on a finite polyhedron. A relation with boundedly-controlled L-groups is also discussed.Comment: This is the version published by Geometry & Topology Monographs on 22 April 200

More examples of discrete co-compact group actions

We survey some results and questions about free actions of infinite groups on products of spheres and euclidean spaces, and give some new co-compact examples

Controlled surgery with trivial local fundamental groups

We provide a proof of the controlled surgery sequence, including stability, in the special case that the local fundamental groups are trivial. Stability is a key ingredient in the construction of exotic homology manifolds by Bryant, Ferry, Mio and Weinberger, but no proof has been available. The development given here is based on work of M. Yamasaki.Comment: 5 page