The main result of this paper is a new and direct proof of the natural transformation
from the surgery exact sequence in topology to the analytic K-theory sequence of
Higson and Roe.
Our approach makes crucial use of analytic properties and new index theorems for
the signature operator on Galois coverings with boundary. These are of independent
interest and form the second main theme of the paper. The main technical novelty is
the use of large-scale index theory for Dirac-type operators that are perturbed by
lower-order operators.
Keywords
signature operator, K-theory, exact surgery sequence, index
classes, rho-classes