  The 1.5 formalism played a key role in the discovery of supergravity and it
has been used to prove the invariance of essentially all supergravity theories
under local supersymmetry. It emerged from the gauging of the super Poincare
group to find supergravity. We review both of these developments as well as the
auxiliary fields for simple supergravity and its most general coupling to
matter using the tensor calculus.

High Energy Physics - Theory