Linear Groups and Square Properties in Rings
Copyright 2016 Betty Jones and Sisters Publishing
A link to full text has been provided for authorized users
In  a proof was given of Fermat’s Two-Square Theorem using the group theoretical structure of the classical modular group. This has been extended in many directions and to other square properties in general rings. In particular in  a two-square theorem was given for the Gaussian integers in terms of when i is a quadratic residue. In this note we examine and survey this technique and the corresponding results and extensions.