$n$-cocoherent rings‎, ‎$n$-cosemihereditary rings and $n$-v-rings

Authors

z. ‎zhu

department of mathematics,jiaxing university,jiaxing,zhejiang province,china,314001

abstract

let $r$ be a ring‎, ‎and let $n‎, ‎d$ be non-negative integers‎. ‎a right $r$-module $m$ is called $(n‎, ‎d)$-projective if $ext^{d+1}_r(m‎, ‎a)=0$ for every $n$-copresented right $r$-module $a$‎. ‎$r$ is called right $n$-cocoherent if every $n$-copresented right $r$-module is $(n+1)$-coprese-nted‎, ‎it is called a right co-$(n,d)$-ring if every right $r$-module is $(n‎, ‎d)$-projective‎. ‎$r$ is called right‎ ‎$n$-cosemihereditary if every submodule of a projective right $r$-module is‎ ‎$(n‎, ‎0)$-projective‎, ‎it is called a right‎ ‎$n$-v-ring if it is a right co-$(n,0)$-ring‎. ‎some properties of $(n‎, ‎d)$-projective modules and $(n‎, ‎d)$-projective dimensions of modules over $n$-cocoherent rings are studied‎. ‎certain characterizations of $n$-copresented modules‎, ‎$(n‎, ‎0)$-projective modules‎, ‎right $n$-cocoherent rings‎, ‎right $n$-cosemihereditary rings‎, ‎as well as right $n$-v-rings are given respectively‎.

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Journal title:
bulletin of the iranian mathematical society

جلد ۴۰، شماره ۴، صفحات ۸۰۹-۸۲۲

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