Structures on M x I (Ex)
Let be a closed oriented topological manifold of dimension and let denote the pseudo-isotopy group of orientation preserving self homeomorphisms of : two self homeomorphisms and are pseudo-isotopic if they extend to a homeomorphism : the group operation is composition. Let
be the subgroup of equivalences classes which are homotopic to the identity.
Exercise 0.1. Using the fact that the topological surgery exact sequence is a long exact sequence of abelian groups show that is abelian.