English

On the Hilbert coefficients, depth of associated graded rings and reduction numbers

Commutative Algebra 2019-09-18 v3

Abstract

Let (R,m)(R,\mathfrak{m}) be a dd-dimensional Cohen-Macaulay local ring, II an m\mathfrak{m}-primary ideal of RR and J=(x1,...,xd)J=(x_1,...,x_d) a minimal reduction of II. We show that if Jd1=(x1,...,xd1)J_{d-1}=(x_1,...,x_{d-1}) and n=1λ(In+1Jd1)/(JInJd1)=i\sum\limits_{n=1}^\infty\lambda{({I^{n+1}\cap J_{d-1}})/({J{I^n} \cap J_{d-1}})=i} where i=0,1, then depth G(I)di1G(I)\geq{d-i-1}. Moreover, we prove that if e2(I)=n=2(n1)λ(In/JIn1)2;e_2(I) = \sum_{n=2}^\infty (n-1) \lambda (I^n/JI^{n-1})-2; or if II is integrally closed and e2(I)=n=2(n1)λ(In/JIn1)ie_2(I) = \sum_{n=2}^\infty (n-1)\lambda({{I^{n}}}/JI^{n-1})-i where i=3,4i=3,4, then e1(I)=n=1λ(In/JIn1)1.e_1(I) = \sum_{n=1}^\infty \lambda(I^n / JI^{n-1})-1. In addition, we show that r(I)r(I) is independent. Furthermore, we study the independence of r(I)r(I) with some other conditions.

Keywords

Cite

@article{arxiv.1703.07961,
  title  = {On the Hilbert coefficients, depth of associated graded rings and reduction numbers},
  author = {Amir Mafi and Dler Naderi},
  journal= {arXiv preprint arXiv:1703.07961},
  year   = {2019}
}

Comments

to appear in JCA