On the singularities of weakly normal varieties

Among the weakly normal varieties (in the sense of Andreotti and Bombieri, 1]) are of particular interest those varieties such that the normalization morphism is unramified outside a subvariety of codimension not less than 2. We describe the singularities of these varieties (called here WN1) by means of analytic equations, tangent cones, analytic branches and we show that any irreducible projective variety is birationally equivalent to a WN1 hypersur face and that a Gorenstein variety is weakly normal if and only if it is WN1.This research was done when the authors were members of G.N.S.A.G.A. of the C.N.R.