Abstract :
Let A be a positively graded, connected affine image-algebra generated in degree one which is a finite module over a central subring R. Let image be the structure sheaf over Proj(R) and Spec image the central Proj. If injdim(A) < ∞, then Spec image has singularities unless the ramification locus of image is pure of codimension one. If gldim(A) < ∞, then the codimension ≥ 2 parts of the ramification locus of image and the singular locus of Spec image coincide.
