English

Multiplicities of weakly graded families of ideals

Commutative Algebra 2025-05-21 v4

Abstract

In this article, we extend the notion of multiplicity for weakly graded families of ideals which are bounded below linearly. In particular, we show that the limit eW(I):=limnd!R(R/In)nde_W(\mathfrak{I}):=\lim\limits_{n\to\infty}d!\frac{\ell_R(R/I_n)}{n^d} exists where I={In}\mathfrak I=\{I_n\} is a bounded below linearly weakly graded families of ideals in a Noetherian local ring (R,m)(R,\mathfrak m) of dimension d1d\geq 1 with dim(N(R^))<d\dim(N(\hat{R}))<d. Furthermore, we prove that ``volume=multiplicity" formula and Minkowski inequality hold for such families of ideals. We explore some properties of eW(J)e_W(\mathfrak J) for weakly graded families of ideals of the form J={(In:K)}\mathfrak J=\{(I_n:K)\} where {In}\{I_n\} is an m\mathfrak m-primary graded family of ideals. We provide a necessary and sufficient condition for the equality in Minkowski inequality for the weakly graded family of ideals of the form J={(In:K)}\mathfrak J=\{(I_n:K)\} where {In}\{I_n\} is a bounded filtration. Moreover, we generalize a result of Rees characterizing the inclusion of ideals with the same multiplicities for the above families of ideals. Finally, we investigate the asymptotic behaviour of the length function R(Hm0(R/(In:K)))\ell_R(H_{\mathfrak m}^0(R/(I_n:K))) where {In}\{I_n\} is a filtration of ideals (not necessarily m\mathfrak m-primary).

Keywords

Cite

@article{arxiv.2411.04831,
  title  = {Multiplicities of weakly graded families of ideals},
  author = {Parangama Sarkar},
  journal= {arXiv preprint arXiv:2411.04831},
  year   = {2025}
}

Comments

Three sentences are added at the end of the proof of Theorem 4.3 (ii) to provide more explanation