Cohomology Vanishing theorems over some rings containing nilpotents

Abstract

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