Moharram Aghapournahr

  1. On the vanishing and finiteness properties of generalized local cohomology modules.

    Authors: Moharram Aghapournahr
    Subjects: Commutative Algebra
    Abstract

    Let $R$ be a commutative noetherian ring, $\fa$ an ideal of $R$ and $M,N$
    finite $R$--modules. We prove that the following statements are equivalent.
    \begin{enumerate} \item[(i)] $\lc^{i}_{\fa}(M,N)$ is finite for all $i< n$.
    \item[(ii)] $\Coass_R(\lc^{i}_{\fa}(M,N)) \subset \V{(\fa)}$ for all $i< n$.
    \item[(iii)] $\lc^{i}_{\fa}(M,N)$ is coatomic for all $i< n$. \end{enumerate}
    If $\pd M$ is finite and $r$ be a non-negative integer such that $r>\pd M$ and
    $\lc^{i}_{\fa}(M,N)$ is finite (resp. minimax) for all $i\geq r$, then
    $\lc^{i}_{\fa}(M,N)$ is zero (resp.

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