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Associated graded rings and connected sums

H. Ananthnarayan, Ela Celikbas, Jai Laxmi, Zheng Yang (2020)

Czechoslovak Mathematical Journal

In 2012, Ananthnarayan, Avramov and Moore gave a new construction of Gorenstein rings from two Gorenstein local rings, called their connected sum. In this article, we investigate conditions on the associated graded ring of a Gorenstein Artin local ring Q , which force it to be a connected sum over its residue field. In particular, we recover some results regarding short, and stretched, Gorenstein Artin rings. Finally, using these decompositions, we obtain results about the rationality of the Poincaré...

Bounds on Bass numbers and their dual

Abolfazl Tehranian, Siamak Yassemi (2007)

Archivum Mathematicum

Let ( R , 𝔪 ) be a commutative Noetherian local ring. We establish some bounds for the sequence of Bass numbers and their dual for a finitely generated R -module.

Bounds on Castelnuovo-Mumford regularity for divisors on rational normal scrolls.

Chikashi Miyazaki (2005)

Collectanea Mathematica

The Castelnuovo-Mumford regularity is one of the most important invariants in studying the minimal free resolution of the defining ideals of the projective varieties. There are some bounds on the Castelnuovo-Mumford regularity of the projective variety in terms of the other basic invariants such as dimension, codimension and degree. This paper studies a bound on the regularity conjectured by Hoa, and shows this bound and extremal examples in the case of divisors on rational normal scrolls.

Cohen-Lenstra sums over local rings

Christian Wittmann (2004)

Journal de Théorie des Nombres de Bordeaux

We study series of the form M | Aut R ( M ) | - 1 | M | - u , where R is a commutative local ring, u is a non-negative integer, and the summation extends over all finite R -modules M , up to isomorphism. This problem is motivated by Cohen-Lenstra heuristics on class groups of number fields, where sums of this kind occur. If R has additional properties, we will relate the above sum to a limit of zeta functions of the free modules R n , where these zeta functions count R -submodules of finite index in R n . In particular we will show that...

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