Localization and Catenarity in Strongly Graded Rings

The objective of this article is the study of localization and catenarity in strongly G-graded rings with Noetherian base ring, where G is a finitely generated, nilpotent and torsionfree group. We generalize some results of Guédénon (2000 Guédénon , T. ( 2000 ). Anneaux munis d'une action de groupe superrésoluble . Algebras Groups and Geometries 17 : 17 – 48 . [CSA]  [Google Scholar]). It follows from Corollary 2.6 that if G is free Abelian of finite rank and A is a commutative strongly G-graded ring with base ring a Noetherian regular integral domain, then A is a Noetherian regular integral domain.     

Localization and Catenarity in Iterated Differential Operator Rings

ABSTRACT

Let k be a field, R an associative k-algebra with identity, Δ a finite set of derivations of R, and R[Θ₁, δ₁] ··· [Θ _n , δ _n ] an iterated differential operator k-algebra over R such that δ _j (Θ _i ) ∈ R[Θ₁, δ₁] ··· [Θ _i?1, δ _i?1]; 1 ≤ i < j ≤ n. If R is Noetherian Δ-hypercentral, then every prime ideal P of A is classically localizable. The aim of this article is to show that under some additional hypotheses on the Δ-prime ideals of R, the local ring A _P is regular in the sense of Robert Walker. We use this result to study the catenarity of A and to compute the numbers μ _i of Bass. Let g be a nilpotent Lie algebra of finite dimension n acting on R by derivations and U(g) the enveloping algebra of g. Then the crossed product of R by U(g) is an iterated differential operator k-algebra as above. In this particular case, our results are known if k has characteristic zero.