The Symmetric Signature

This is a dissertation in commutative algebra. The author introduces a new numerical invariant for local rings called symmetric signature. Given a local ring, the symmetric signature is defined by looking at the maximal free splitting of reflexive symmetric powers of the top-dimensional syzygy module of the residue field. The main motivation for this work is given by the F-signature, an important numerical invariant for local rings of positive characteristic which has been largely studied in the last decade. The dissertation contains a computation of the symmetric signature for two-dimensional ADE singularities and for cones over elliptic curves. In both cases, the values obtained coincide with the F-signature of such rings in positive characteristic. The thesis presents also a self-contained exposition of the Auslander correspondence, which is one of the main methods employed.