English

First Coefficient ideals and $R_1$ property of Rees algebras

Commutative Algebra 2024-08-13 v1

Abstract

Let (A,m)(A,\mathfrak{m}) be an excellent normal local ring of dimension d2d \geq 2 with infinite residue field. Let II be an m\mathfrak{m}-primary ideal. Then the following assertions are equivalent: (i) The extended Rees algebra A[It,t1]A[It, t^{-1}] is R1R_1. (ii) The Rees algebra A[It]A[It] is R1R_1. (iii) Proj(A[It])Proj(A[It]) is R1R_1. (iv) (In)=(In)1(I^n)^* = (I^n)_1 for all n1n \geq 1. Here (In)(I^n)^* is the integral closure of InI^n and (In)1(I^n)_1 is the first coefficient ideal of InI^n.

Keywords

Cite

@article{arxiv.2408.05532,
  title  = {First Coefficient ideals and $R_1$ property of Rees algebras},
  author = {Tony J. Puthenpurakal},
  journal= {arXiv preprint arXiv:2408.05532},
  year   = {2024}
}