Let A be a commutative Noetherian local ring containing a field of characteristic p > 0. The integer invariants λi,j(A) have been introduced in an old paper of ours. In this paper we completely describe λd,d(A) where d = dimA in terms of the topology of SpecA.

We show that each R-module is n-flat (resp., weakly n-flat) if and only if R is an (n,n− 1)-ring (resp., a weakly (n,n− 1)-ring). We also give a new characterization of n-von Neumann regular rings and a characterization of weak n-von Neumann regular rings for (CH)-rings and for local rings. Finally, we show that in a class of principal rings and a class of local Gaussian rings, a weak n-von Neu...