  Individual spinors in a SU(2) spin network are described by their relations
to the background spin network. A 'covariant' formulation of these relations
yields the de Sitter group SO(3,2) as the fundamental symmetry group. Locally
this symmetry group is approximated by the Poincare group, which leaves
invariant (certain) clusters of spinors. The calculated masses of these
clusters reproduce the lepton spectrum. Corrections to the approximate Poincare
group, based on the exact SO(3,2) symmetry, deliver interaction terms,
identical to those of the standard model. In addition, gravitation is obtained.
The calculation of the fine-structure constant reproduces Wyler's formula.
