On the minimaxness and coatomicness of local cohomology modules

summary:Let $R$ be a commutative Noetherian ring, $I$ an ideal of $R$ and $M$ an $R$-module. We wish to investigate the relation between vanishing, finiteness, Artinianness, minimaxness and $\mathcal {C}$-minimaxness of local cohomology modules. We show that if $M$ is a minimax $R$-module, then the local-global principle is valid for minimaxness of local cohomology modules. This implies that if $n$ is a nonnegative integer such that $(H^i_I(M))_{\frak m}$ is a minimax $R_{\frak m}$-module for all $\frak m \in {\rm Max} (R)$ and for all $i < n$, then the set ${\rm Ass}_R(H^n_I(M))$ is finite. Also, if $H^i_I(M)$ is minimax for all $i \geq n \geq 1$, then $H^i_I(M)$ is Artinian for $i \geq n$. It is shown that if $M$ is a $\mathcal {C}$-minimax module over a local ring such that $H^i_I(M)$ are $\mathcal {C}$-minimax modules for all $i < n$ (or $i\geq n$), where $n\geq 1$, then they must be minimax. Consequently, a vanishing theorem is proved for local cohomology modules