1. Introduction. We present two closely related results connecting homological dimension theory and the ideal theory of noetherian rings. The first, Proposition 4.1, asserts that the only ideals of finite homological dimension in a local ring whose associated prime ideals all have grade one are of the form aR:bR. The second, Proposition 4.3, asserts that if R is a noetherian integral domain, th...

Let F = {Fn} be a multiplicative filtration of a local ring such that the Rees algebra R(F) is Noetherian. We recall Burch’s inequality for F and give an upper bound of the a-invariant of the associated graded ring a(G(F)) using a reduction system of F . Applying those results, we study the symbolic Rees algebra of certain ideals of dimension 2.

In this paper, we extend the well-known Hilbert’s syzygy theorem to the Gorenstein homological dimensions of rings. Also, we study the Gorenstein homological dimensions of direct products of rings. Our results generate examples of non-Noetherian rings of finite Gorenstein dimensions and infinite classical weak dimension.

For a commutative Noetherian local ring we define and study the class of modules having reducible complexity, a class containing all modules of finite complete intersection dimension. Various properties of this class of modules are given, together with results on the vanishing of homology and cohomology.

A semi-dualizing module over a commutative noetherian ringA is a finitely generated module C with RHomA(C,C) ≃ A in the derived category D(A). We show how each such module gives rise to three new homological dimensions which we call C–Gorenstein projective, C–Gorenstein injective, and C–Gorenstein flat dimension, and investigate the properties of these dimensions.

We consider random hermitian matrices in which distant abovediagonal entries are independent but nearby entries may be correlated. We find the limit of the empirical distribution of eigenvalues by combinatorial methods. We also prove that the limit has algebraic Stieltjes transform by an argument based on dimension theory of noetherian local rings.

Let D be a Noetherian domain containing a field, a ∈ D a nonzero nonunit and z an indeterminate over D. We prove that the generic fiber of the extension D[[z]] →֒ D[1/a][[z]] has dimension ≥ dim(D/aD). 2000 Mathematics Subject Classification: 13F25, 13J10.

Let G be a connected reductive linear algebraic group over a field k of characteristic p > 0. Let p be large enough with respect to the root system. We show that if a finitely generated commutative k-algebra A with G-action has good filtration, then any noetherian A-module with compatible G-action has finite good filtration dimension.

We show that standard arguments for deformations based on dimension counts can also be applied over a (not necessarily Noetherian) valuation ring A of rank 1. Key intermediate results are a principal ideal theorem for schemes of finite type over A, and a theorem on subadditivity of intersection codimension for schemes smooth over A.

We prove that cellular Noetherian algebras with finite global dimension are split quasi-hereditary over a regular commutative ring Krull and their structure is unique, up to equivalence. In the process, we establish algebra semi-perfect if only ground local ring. give formula determine of (with dimension) in terms finite-dimensional algebras. For general case, upper bounds for finitistic arbitr...