On Auslander modules of normal surface singularities

Abstract We study thefundamental sequences of normal surface singularities. Our main result asserts that for rational singularities (with a technical side-condition) and for minimally elliptic singularities the middle termA, theAuslander module, is isomorphic to the module of Zariski differentials if and only if the singularity is quasihomogeneous.