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Vietnam Journal of Mathematics 35:2(2007) 215-222
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H-Cofinitely Supplemented Modules
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Muhammet Tamer Kosan
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Abstract.
Let $M$ be a right $R$-module. We call $M$ {\it $H$-cofinitely supplemented}
if for very cofinite
submodule $A$ of $M$ (i.e. the factor module $M/A$ is
finitely
generated) there exists a direct summand $D$ of $M$ such that
$M=A+X$
holds if and only if $M=D+X$. It is shown that in this
paper: $(1)$ Let $M$
be an $H$-cofinitely supplemented Duo module. Then every direct summand of $M$
is $H$-cofinitely supplemented
module. $(2)$ Let $M=M_1\oplus M_2$ be a Duo module.
If $M_1$ and $M_2$ are $H$-cofinitely supplemented modules, then $M$ is
$H$-cofinitely
supplemented. $(3)$ Assume $Rad(M)<< M$. Then $M$ is $H$-cofinitely supplemented
if and only if every cofinite
submodule of $M/Rad(M)$ is direct summand and each
cofinite direct
summand of $M/Rad(M)$ lifts to a direct summand of $M$. In
addition,
let $M$ be a duo right $R$-module. $M$ is $H$-cofinitely supplemented if and only
if
every maximal submodule of $M$ has an $H$-supplement in $M$.
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2000 Mathematics Subject Classification: 16D99.
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Keywords: Duo modules, $H$-supplemented modules, $H$-cofinitely supplemented modules.
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