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Acta Mathematica Vietnamica

SOME PROPERTIES OF GENERALIZED LOCAL COHOMOLOGY MODULES

icon-email AMIR MAFI

Abstract

Let R be a commutative Noetherian ring, a an ideal of R,M and N be two finitely generated R-modules. Let t be a positive integer. We prove that if R is local with maximal ideal m and MRN is of finite length then Hmt(M,N) is of finite length for all t0 and
lR(Hmt(M,N))i=0tlR(ExtRi(M,Hmti(N))).

This yields lR(Hmt(M,N))=lR(ExtRt(M,N)).

Additionally, we show that ExtRi(R/a,N) is Artinian for all it if and only if Hai(M,N) is Artinian for all it. Moreover, we show that whenever dim(R/a)=0 then Hat(M,N) is Artinian for all t0.