Stably Free Modules over the Klein Bottle

Introduction
Constructing a Stably Free Module
Applications to the Klein Bottle
The Ring ZG
In light of the presentation of G,
ZG = Z[y, y −1 ][x, x −1 ; σ]
and σ is the isomorphism induced by
In particular,
as polynomials in ZG.
σ : y ↦−→ y −1 .
yn = ny, ∀n ∈ Z
xn = nx, ∀n ∈ Z
yx = xy −1
Andrew Misseldine Stably Free Modules over the Klein Bottle