DISCRETE VALUATION RINGS AND MODULES OF DIFFERENTIALS

The module of Kahler differentials of a commutative G-algebra X is ess entially described by two cardinals and two integers when X is a valua tion ring and when the residue extension is good enough. The first car dinal and the two integers have been described by R. Berger and E. Kun z. The last cardinal deals with the divisible part of the torsion of t he module of differentials. It is proved to be finite and given by an equality involving the Krull dimension and the module of imperfection. (C) 1998 Academic Press.