English

Cohomology Vanishing theorems over some rings containing nilpotents

Commutative Algebra 2025-04-21 v1

Abstract

(1) Let (A,m)(A,\mathfrak{m}) be complete Noetherian local ring of dimension dd and let PP be a prime ideal with GP(A)=n0Pn/Pn+1G_P(A) = \bigoplus_{n \geq 0}P^n/P^{n+1} a domain. Fix r1r \geq 1. If JJ is a homogeneous ideal of GPr(A)G_{P^r}(A) with dim GPr(A)/J>0\text{dim} \ G_{P^r}(A)/J > 0 then the local cohomology module HJd(GPr(A))=0H^d_J(G_{P^r}(A)) = 0. (2) Let A=K[[X1,,Xd]]A = K[[X_1, \ldots,X_d]] and let m=(X1,,Xd)\mathfrak{m} = (X_1, \ldots, X_d). Assume KK is separably closed. Fix r1r \geq 1. Let JJ be a homogeneous ideal of Gmr(A)G_{\mathfrak{m}^r}(A). We show that local cohomology modules HJj(Gmr(A))=0H^{j}_J(G_{\mathfrak{m}^r}(A)) = 0 for jd1j \geq d -1 if and only if dim Gmr(A)/J2\text{dim} \ G_{\mathfrak{m}^r}(A)/J \geq 2 and Proj Gmr(A)/J\text{Proj}\ G_{\mathfrak{m}^r}(A)/J is connected.

Keywords

Cite

@article{arxiv.2504.13566,
  title  = {Cohomology Vanishing theorems over some rings containing nilpotents},
  author = {Tony J. Puthenpurakal},
  journal= {arXiv preprint arXiv:2504.13566},
  year   = {2025}
}