English

On asymptotic depth of integral closure filtration and an application

Commutative Algebra 2017-09-20 v1

Abstract

Let (A,m)(A,\mathfrak{m}) be an analytically unramified formally equidimensional Noetherian local ring with  depth A2\ depth \ A \geq 2. Let II be an m\mathfrak{m}-primary ideal and set II^* to be the integral closure of II. Set G(I)=n0(In)/(In+1)G^*(I) = \bigoplus_{n\geq 0} (I^n)^*/(I^{n+1})^* be the associated graded ring of the integral closure filtration of II. We prove that  depth G(In)2\ depth \ G^*(I^n) \geq 2 for all n0n \gg 0. As an application we prove that if AA is also an excellent normal domain containing an algebraically closed field isomorphic to A/\mA/\m then there exists s0s_0 such that for all ss0s \geq s_0 and JJ is an integrally closed ideal \emph{strictly} containing (ms)(\mathfrak{m}^s)^* then we have a strict inequality μ(J)<μ((ms))\mu(J) < \mu((\mathfrak{m}^s)^*) (here μ(J)\mu(J) is the number of minimal generators of JJ).

Keywords

Cite

@article{arxiv.1709.06244,
  title  = {On asymptotic depth of integral closure filtration and an application},
  author = {Tony J. Puthenpurakal},
  journal= {arXiv preprint arXiv:1709.06244},
  year   = {2017}
}