The second Hilbert coefficient of modules with almost maximal depth

2019 ◽  
Vol 18 (12) ◽  
pp. 1950240
Author(s):  
Van Duc Trung
Keyword(s):  
Lower Bound ◽  
Local Ring ◽  
Upper Bound ◽  
Primary Ideal ◽  
Finitely Generated ◽  
Dimension Formula ◽  
Maximal Depth ◽  
Graded Module ◽  
Hilbert Coefficient

Let [Formula: see text] be a good [Formula: see text]-filtration of a finitely generated [Formula: see text]-module [Formula: see text] of dimension [Formula: see text], where [Formula: see text] is a local ring and [Formula: see text] is an [Formula: see text]-primary ideal of [Formula: see text]. In the case of depth [Formula: see text], we give an upper bound for the second Hilbert coefficient [Formula: see text] generalizing the results by Huckaba–Marley, and Rossi–Valla proved that [Formula: see text] is Cohen–Macaulay. We also give a condition for the equality, which relates to the depth of the associated graded module [Formula: see text]. A lower bound on [Formula: see text] is proved generalizing a result by Rees and Narita.

scholarly journals Upper bounds of Hilbert coefficients and Hilbert functions

2008 ◽  
Vol 145 (1) ◽  
pp. 87-94 ◽  
Author(s):  
JUAN ELIAS
Keyword(s):  
Finite Number ◽  
Local Ring ◽  
Maximal Ideal ◽  
Upper Bound ◽  
Upper Bounds ◽  
Primary Ideal ◽  
Hilbert Functions ◽  
Hilbert Coefficients ◽  
Hilbert Coefficient

AbstractLet (R, m) be a d-dimensional Cohen–Macaulay local ring. In this paper we prove, in a very elementary way, an upper bound of the first normalized Hilbert coefficient of a m-primary ideal I ⊂ R that improves all known upper bounds unless for a finite number of cases, see Remark 2.3. We also provide new upper bounds of the Hilbert functions of I extending the known bounds for the maximal ideal.

scholarly journals Maximal depth property of finitely generated modules

2018 ◽  
Vol 17 (11) ◽  
pp. 1850202 ◽  
Author(s):  
Ahad Rahimi
Keyword(s):  
Local Ring ◽  
Finitely Generated ◽  
Noetherian Local Ring ◽  
Maximal Depth ◽  
Finitely Generated Modules ◽  
Associated Prime

Let [Formula: see text] be a Noetherian local ring and [Formula: see text] a finitely generated [Formula: see text]-module. We say [Formula: see text] has maximal depth if there is an associated prime [Formula: see text] of [Formula: see text] such that depth [Formula: see text]. In this paper, we study finitely generated modules with maximal depth. It is shown that the maximal depth property is preserved under some important module operations. Generalized Cohen–Macaulay modules with maximal depth are classified. Finally, the attached primes of [Formula: see text] are considered for [Formula: see text].

On the Multiplicity and the Cohen–Macaulayness of Fiber Cones of Graded Modules

2021 ◽  
Vol 28 (01) ◽  
pp. 13-32
Author(s):  
Nguyen Tien Manh
Keyword(s):  
Local Ring ◽  
Maximal Ideal ◽  
Primary Ideal ◽  
Graded Algebra ◽  
Finitely Generated ◽  
Ideal Formula ◽  
Noetherian Local Ring ◽  
Graded Modules ◽  
Fiber Cone

Let [Formula: see text] be a Noetherian local ring with maximal ideal [Formula: see text], [Formula: see text] an ideal of [Formula: see text], [Formula: see text] an [Formula: see text]-primary ideal of [Formula: see text], [Formula: see text] a finitely generated [Formula: see text]-module, [Formula: see text] a finitely generated standard graded algebra over [Formula: see text] and [Formula: see text] a finitely generated graded [Formula: see text]-module. We characterize the multiplicity and the Cohen–Macaulayness of the fiber cone [Formula: see text]. As an application, we obtain some results on the multiplicity and the Cohen–Macaulayness of the fiber cone[Formula: see text].

Annihilator of local cohomology of homogeneous parts of a graded module

2020 ◽  
pp. 2150092
Author(s):  
Tran Do Minh Chau ◽  
Nguyen Thi Kieu Nga ◽  
Le Thanh Nhan
Keyword(s):  
Asymptotic Stability ◽  
Local Ring ◽  
Local Cohomology ◽  
Prime Ideals ◽  
Finitely Generated ◽  
Graded Ring ◽  
Noetherian Local Ring ◽  
Graded Module

Let [Formula: see text] be a homogeneous graded ring, where [Formula: see text] is a Noetherian local ring. Let [Formula: see text] be a finitely generated graded [Formula: see text]-module. For [Formula: see text] set [Formula: see text]. Denote by [Formula: see text] the set of all prime ideals of [Formula: see text] containing [Formula: see text]. For [Formula: see text], let [Formula: see text] be the set of all [Formula: see text] such that [Formula: see text] In this paper, we prove that the sets [Formula: see text] and [Formula: see text] do not depend on [Formula: see text] for [Formula: see text]. We show that the annihilators [Formula: see text], [Formula: see text] are eventually stable, where [Formula: see text] for [Formula: see text]. As an application, we prove the asymptotic stability of some loci contained in the non-Cohen–Macaulay locus of [Formula: see text].

Cofiniteness of Local Cohomology Modules

2014 ◽  
Vol 21 (04) ◽  
pp. 605-614 ◽  
Author(s):  
Kamal Bahmanpour ◽  
Reza Naghipour ◽  
Monireh Sedghi
Keyword(s):  
Local Ring ◽  
Local Cohomology ◽  
Partial Answer ◽  
Finitely Generated ◽  
Finitely Generated Module ◽  
Noetherian Local Ring ◽  
Dimension Formula ◽  
Complete Local Ring ◽  
Local Cohomology Modules ◽  
Cohomology Modules

Let M be a non-zero finitely generated module over a commutative Noetherian local ring (R, 𝔪). In this paper we consider when the local cohomology modules are finitely generated. It is shown that if t ≥ 0 is an integer and [Formula: see text], then [Formula: see text] is not 𝔭-cofinite. Then we obtain a partial answer to a question raised by Huneke. Namely, if R is a complete local ring, then [Formula: see text] is finitely generated if and only if 0 ≤ n ∉ W, where [Formula: see text]. Also, we show that if J ⊆ I are 1-dimensional ideals of R, then [Formula: see text] is J-cominimax, and [Formula: see text] is finitely generated (resp., minimax) if and only if [Formula: see text] is finitely generated for all [Formula: see text] (resp., [Formula: see text]). Moreover, the concept of the J-cofiniteness dimension [Formula: see text] of M relative to I is introduced, and we explore an interrelation between [Formula: see text] and the filter depth of M in I. Finally, we show that if R is complete and dim M/IM ≠ 0, then [Formula: see text].

scholarly journals ON THE ASYMPTOTIC BEHAVIOR OF THE LINEARITY DEFECT

2017 ◽  
Vol 230 ◽  
pp. 35-47 ◽  
Author(s):  
HOP D. NGUYEN ◽  
THANH VU
Keyword(s):  
Asymptotic Behavior ◽  
Local Ring ◽  
General Result ◽  
Free Resolution ◽  
Graded Algebra ◽  
Regular Local Ring ◽  
Finitely Generated ◽  
Minimal Free Resolution ◽  
Noetherian Local Ring ◽  
Graded Module

This work concerns the linearity defect of a module $M$ over a Noetherian local ring $R$, introduced by Herzog and Iyengar in 2005, and denoted $\text{ld}_{R}M$. Roughly speaking, $\text{ld}_{R}M$ is the homological degree beyond which the minimal free resolution of $M$ is linear. It is proved that for any ideal $I$ in a regular local ring $R$ and for any finitely generated $R$-module $M$, each of the sequences $(\text{ld}_{R}(I^{n}M))_{n}$ and $(\text{ld}_{R}(M/I^{n}M))_{n}$ is eventually constant. The first statement follows from a more general result about the eventual constancy of the sequence $(\text{ld}_{R}C_{n})_{n}$ where $C$ is a finitely generated graded module over a standard graded algebra over $R$.

scholarly journals Hilbert-Samuel function and Grothendieck group

2000 ◽  
Vol 43 (1) ◽  
pp. 73-94
Author(s):  
Koji Nishida
Keyword(s):  
Local Ring ◽  
Grothendieck Group ◽  
Residue Field ◽  
Primary Ideal ◽  
Hilbert Polynomial ◽  
Associated Graded Ring ◽  
Graded Ring ◽  
Noetherian Local Ring ◽  
Graded Module ◽  
Primary Ideals

AbstractLet (A, m) be a Noetherian local ring such that the residue field A/m is infinite. Let I be arbitrary ideal in A, and M a finitely generated A-module. We denote by ℓ(I, M) the Krull dimension of the graded module ⊕n≥0InM/mInM over the associated graded ring of I. Notice that ℓ(I, A) is just the analytic spread of I. In this paper, we define, for 0 ≤ i ≤ ℓ = ℓ(I, M), certain elements ei(I, M) in the Grothendieck group K0(A/I) that suitably generalize the notion of the coefficients of Hilbert polynomial for m-primary ideals. In particular, we show that the top term eℓ (I, M), which is denoted by eI(M), enjoys the same properties as the ordinary multiplicity of M with respect to an m-primary ideal.

On the Hilbert Coefficients and Betti Numbers of the Stanley-Reisner Ring of a Matroid Complex

2013 ◽  
Vol 20 (01) ◽  
pp. 47-58
Author(s):  
N. Shirmohammadi
Keyword(s):  
Polynomial Ring ◽  
Upper Bound ◽  
Betti Number ◽  
Betti Numbers ◽  
Free Resolution ◽  
Finitely Generated ◽  
Hilbert Coefficients ◽  
Hilbert Coefficient

Let S=K[x1,…,xn] be a polynomial ring. Herzog and Zheng conjectured that the i-th Hilbert coefficient of a finitely generated graded Cohen-Macaulay S-module N generated in degree 0 is bounded by the functions of the minimal and maximal shifts in the minimal graded free resolution of N over S and the 0-th Betti number of N. Also, Römer asked whether under the Cohen-Macaulay assumption the i-th Betti number of S/I, where I ⊂ S is a graded ideal, can be bounded by the functions of the minimal and maximal shifts of S/I. In this paper, we provide elementary proofs to establish Herzog and Zheng's conjecture and the upper bound part of Römer's question for the Stanley-Reisner ring of a matroid complex.

The Joint Reduction Number and Upper Bounds of Hilbert Series of Fiber Cones

2013 ◽  
Vol 20 (04) ◽  
pp. 653-662
Author(s):  
Guangjun Zhu
Keyword(s):  
Local Ring ◽  
Upper Bound ◽  
Hilbert Series ◽  
Upper Bounds ◽  
Primary Ideal ◽  
Reduction Number ◽  
Joint Reduction

Let (R,𝔪) be a Cohen-Macaulay local ring of dimension d > 0, I an 𝔪-primary ideal of R and K an ideal containing I. Let a1,…,ad be a joint reduction of (I[d-1]|K), and set L=(a1,…,ad), J=(a1,…,ad-1). When depth G(I) ≥ d-1 and depth FK(I) ≥ d-2, we show that the lengths [Formula: see text], [Formula: see text] and the joint reduction number rL(I|K) are independent of L. In the general case, we give an upper bound of the Hilbert series of FK(I). When depth G(I) ≥ d-1, we also provide a characterization, in terms of the Hilbert series of FK(I), of the condition depth FK(I) ≥ d-1.

Regular sequences and vanishing of the homological functors

2018 ◽  
Vol 17 (11) ◽  
pp. 1850220
Author(s):  
Kamal Bahmanpour
Keyword(s):  
Positive Integer ◽  
Local Ring ◽  
Regular Sequence ◽  
Finitely Generated ◽  
Noetherian Local Ring ◽  
Dimension Formula ◽  
Regular Sequences ◽  
Equivalent Conditions

Let [Formula: see text] be a Noetherian local ring of dimension [Formula: see text] and let [Formula: see text] be a nonzero finitely generated [Formula: see text]-module. Let [Formula: see text] be a positive integer and let [Formula: see text] be an [Formula: see text]-regular sequence. In this paper we shall present some equivalent conditions for the vanishing of the [Formula: see text]-modules [Formula: see text] and [Formula: see text].

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