Whitehead torsion (Ex)
From Manifold Atlas
Show that for the generator is a unit and hence defines an element in . Prove that we obtain a well-defined map
by sending the class represented by the -automorphism to , where is the -linear map
with respect to the -action on given by multiplication with . Finally show that generates an infinite cyclic subgroup in .
This is a detailed version of [Milnor1966, Example 6.6] and [Kreck&Lück2005, Ex 5.4].