Regular Sequences, Projective Dimension, and Criteria for Regularity of Local Rings

1994 ◽  
Vol 120 (4) ◽  
pp. 1017
Author(s):  
P. Jothilingam ◽  
S. Mangayarcarassy
Keyword(s):  
Projective Dimension ◽  
Local Rings ◽  
Regular Sequences

scholarly journals On Regular Sequences

1966 ◽  
Vol 27 (1) ◽  
pp. 355-356 ◽  
Author(s):  
J. Dieudonné
Keyword(s):  
Algebraic Geometry ◽  
Noetherian Ring ◽  
Regular Sequence ◽  
Local Rings ◽  
Regular Sequences

The concept of regular sequence of elements of a ring A (first introduced by Serre under the name of A-sequence [2]), has far-reaching uses in the theory of local rings and in algebraic geometry. It seems, however, that it loses much of its importance when A is not a noetherian ring, and in that case, it probably should be superseded by the concept of quasi-regular sequence [1].

scholarly journals Characterizing local rings via homological dimensions and regular sequences

2006 ◽  
Vol 207 (1) ◽  
pp. 99-108 ◽  
Author(s):  
Shokrollah Salarian ◽  
Sean Sather-Wagstaff ◽  
Siamak Yassemi
Keyword(s):  
Local Rings ◽  
Regular Sequences ◽  
Homological Dimensions

REGULAR LOCAL ALGEBRAS OVER VALUATION DOMAINS: WEAK DIMENSION AND REGULAR SEQUENCES

2008 ◽  
Vol 07 (05) ◽  
pp. 575-591
Author(s):  
HAGEN KNAF
Keyword(s):  
Projective Dimension ◽  
Regular Sequence ◽  
Homological Dimension ◽  
Finitely Generated ◽  
Prüfer Domain ◽  
Regular Sequences ◽  
Local Algebras ◽  
Weak Dimension ◽  
Valuation Domains ◽  
Finitely Presented

A local ring O is called regular if every finitely generated ideal I ◃ O possesses finite projective dimension. In the article localizations O = Aq, q ∈ Spec A, of a finitely presented, flat algebra A over a Prüfer domain R are investigated with respect to regularity: this property of O is shown to be equivalent to the finiteness of the weak homological dimension wdim O. A formula to compute wdim O is provided. Furthermore regular sequences within the maximal ideal M ◃ O are studied: it is shown that regularity of O implies the existence of a maximal regular sequence of length wdim O. If q ∩ R has finite height, then this sequence can be chosen such that the radical of the ideal generated by its members equals M. As a consequence it is proved that if O is regular, then the factor ring O/(q ∩ R)O, which is noetherian, is Cohen–Macaulay. If in addition (q ∩ R)Rq ∩ R is not finitely generated, then O/(q ∩ R)O itself is regular.

scholarly journals On modules of finite projective dimension

2015 ◽  
Vol 219 ◽  
pp. 87-111 ◽  
Author(s):  
S. P. Dutta
Keyword(s):  
Local Ring ◽  
Projective Dimension ◽  
Order Ideal ◽  
Local Rings ◽  
Minimal Generator ◽  
Finite Projective Dimension ◽  
Special Cases ◽  
Nonzero Divisor ◽  
Finitely Generated Modules ◽  
Minimal Generators

AbstractWe address two aspects of finitely generated modules of finite projective dimension over local rings and their connection in between: embeddability and grade of order ideals of minimal generators of syzygies. We provide a solution of the embeddability problem and prove important reductions and special cases of the order ideal conjecture. In particular, we derive that, in any local ringRof mixed characteristicp> 0, wherepis a nonzero divisor, ifIis an ideal of finite projective dimension overRandp𝜖Iorpis a nonzero divisor onR/I, then every minimal generator ofIis a nonzero divisor. Hence, ifPis a prime ideal of finite projective dimension in a local ringR, then every minimal generator ofPis a nonzero divisor inR.

scholarly journals On modules of finite projective dimension

2015 ◽  
Vol 219 ◽  
pp. 87-111
Author(s):  
S. P. Dutta
Keyword(s):  
Local Ring ◽  
Projective Dimension ◽  
Order Ideal ◽  
Local Rings ◽  
Minimal Generator ◽  
Finite Projective Dimension ◽  
Special Cases ◽  
Nonzero Divisor ◽  
Finitely Generated Modules ◽  
Minimal Generators

AbstractWe address two aspects of finitely generated modules of finite projective dimension over local rings and their connection in between: embeddability and grade of order ideals of minimal generators of syzygies. We provide a solution of the embeddability problem and prove important reductions and special cases of the order ideal conjecture. In particular, we derive that, in any local ring R of mixed characteristic p > 0, where p is a nonzero divisor, if I is an ideal of finite projective dimension over R and p 𝜖 I or p is a nonzero divisor on R/I, then every minimal generator of I is a nonzero divisor. Hence, if P is a prime ideal of finite projective dimension in a local ring R, then every minimal generator of P is a nonzero divisor in R.

ABSOLUTE, RELATIVE, AND TATE COHOMOLOGY OF MODULES OF FINITE GORENSTEIN DIMENSION

2002 ◽  
Vol 85 (2) ◽  
pp. 393-440 ◽  
Author(s):  
LUCHEZAR L. AVRAMOV ◽  
ALEX MARTSINKOVSKY
Keyword(s):  
Exact Sequence ◽  
Projective Dimension ◽  
Subject Classification ◽  
Local Rings ◽  
Tate Cohomology ◽  
Gorenstein Dimension ◽  
Relative Cohomology ◽  
Numerical Invariants ◽  
The One ◽  
Finitely Generated Modules

We study finitely generated modules $M$ over a ring $R$, noetherian on both sides. If $M$ has finite Gorenstein dimension $\mbox{G-dim}_RM$ in the sense of Auslander and Bridger, then it determines two other cohomology theories besides the one given by the absolute cohomology functors ${\rm Ext}^n_R(M,\ )$. Relative cohomology functors ${\rm Ext}^n_{\mathcal G}(M,\ )$ are defined for all non-negative integers $n$; they treat the modules of Gorenstein dimension $0$ as projectives and vanish for $n > \mbox{G-dim}_RM$. Tate cohomology functors $\widehat{\rm Ext}^n_R(M,\ )$ are defined for all integers $n$; all groups $\widehat{\rm Ext}^n_R(M,N)$ vanish if $M$ or $N$ has finite projective dimension. Comparison morphisms $\varepsilon_{\mathcal G}^n \colon {\rm Ext}^n_{\mathcal G}(M,\ ) \to {\rm Ext}^n_R(M,\ )$ and $\varepsilon_R^n \colon {\rm Ext}^n_R(M,\ ) \to \widehat{\rm Ext}^n_R(M,\ )$ link these functors. We give a self-contained treatment of modules of finite G-dimension, establish basic properties of relative and Tate cohomology, and embed the comparison morphisms into a canonical long exact sequence $0 \to {\rm Ext}^1_{\mathcal G}(M,\ ) \to \cdots \to {\rm Ext}^n_{\mathcal G}(M,\ ) \to {\rm Ext}^n_R(M,\ ) \to \widehat{\rm Ext}^n_R(M,\ ) \to {\rm Ext}^{n+1}_{\mathcal G}(M,\ ) \to \cdots$. We show that these results provide efficient tools for computing old and new numerical invariants of modules over commutative local rings. 2000 Mathematical Subject Classification: 16E05, 13H10, 18G25.

scholarly journals F-THRESHOLDS OF GRADED RINGS

2016 ◽  
Vol 229 ◽  
pp. 141-168 ◽  
Author(s):  
ALESSANDRO DE STEFANI ◽  
LUIS NÚÑEZ-BETANCOURT
Keyword(s):  
Characteristic Zero ◽  
Projective Dimension ◽  
Graded Rings ◽  
Projective Varieties ◽  
Regular Sequences ◽  
Serre’S Condition ◽  
Regular Rings

The $a$-invariant, the $F$-pure threshold, and the diagonal $F$-threshold are three important invariants of a graded $K$-algebra. Hirose, Watanabe, and Yoshida have conjectured relations among these invariants for strongly $F$-regular rings. In this article, we prove that these relations hold only assuming that the algebra is $F$-pure. In addition, we present an interpretation of the $a$-invariant for $F$-pure Gorenstein graded $K$-algebras in terms of regular sequences that preserve $F$-purity. This result is in the spirit of Bertini theorems for projective varieties. Moreover, we show connections with projective dimension, Castelnuovo–Mumford regularity, and Serre’s condition $S_{k}$. We also present analogous results and questions in characteristic zero.

scholarly journals Local rings with quasi-decomposable maximal ideal

2018 ◽  
Vol 168 (2) ◽  
pp. 305-322 ◽  
Author(s):  
SAEED NASSEH ◽  
RYO TAKAHASHI
Keyword(s):  
Direct Summand ◽  
Local Ring ◽  
Maximal Ideal ◽  
Projective Dimension ◽  
Complete Classification ◽  
Local Rings ◽  
Finitely Generated ◽  
Noetherian Local Ring ◽  
Direct Sum

AbstractLet (R, 𝔪) be a commutative noetherian local ring. In this paper, we prove that if 𝔪 is decomposable, then for any finitely generated R-module M of infinite projective dimension 𝔪 is a direct summand of (a direct sum of) syzygies of M. Applying this result to the case where 𝔪 is quasi-decomposable, we obtain several classifications of subcategories, including a complete classification of the thick subcategories of the singularity category of R.

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