نتایج جستجو برای: semiperfect
تعداد نتایج: 84 فیلتر نتایج به سال:
Let $R$ be a ring and $M$ a right $R$-module. We call $M$, coretractable relative to $overline{Z}(M)$ (for short, $overline{Z}(M)$-coretractable) provided that, for every proper submodule $N$ of $M$ containing $overline{Z}(M)$, there is a nonzero homomorphism $f:dfrac{M}{N}rightarrow M$. We investigate some conditions under which the two concepts coretractable and $overline{Z}(M)$-coretractable...
In this paper $S$ is a monoid with a left zero and $A_S$ (or $A$) is a unitary right $S$-act. It is shown that a monoid $S$ is right perfect (semiperfect) if and only if every (finitely generated) strongly flat right $S$-act is quasi-projective. Also it is shown that if every right $S$-act has a unique zero element, then the existence of a quasi-projective cover for each right act implies that ...
We investigate two invariants of Noetherian semiperfect rings, namely the depth and a new invariant we call “delooping level”. These give lower upper bounds for finitistic dimension, respectively. As first theorems, necessary sufficient criterion delooping level to be finite in terms splitting unit map related adjunction, use this torsionfreeness finiteness. further relate these Auslander–Bridg...
we call a ring $r$ right generalized semiperfect if every simple right $r$-module is an epimorphic image of a flat right $r$-module with small kernel, that is, every simple right $r$-module has a flat $b$-cover. we give some properties of such rings along with examples. we introduce flat strong covers as flat covers which are also flat $b$-covers and give characterizations of $a$-perfe...
By maintaining appropriate data structures, we develop constant-time transposition oracles that answer whether or not two adjacent vertices in a simple elimination ordering (SEO) or a semiperfect elimination ordering (semiPEO) can be swapped to produce a new SEO or semiPEO, respectively. Combined with previous results regarding convex geometries and antimatroids, this allows us to list all SEOs...
for the first time nakayama introduced qf-ring. in 1967 carl. faith and elbert a. walker showed that r is qf-ring if and only if each injective right r-module is projective if and only if each injective left r-modules is projective. in 1987 s.k.jain and s.r.lopez-permouth proved that every ring homomorphic images of r has the property that each cyclic s-module is essentialy embeddable in dire...
A commutative ring A is said to be clean if every element of A can be written as a sum of a unit and an idempotent. This definition dates back to 1977 where it was introduced by W. K. Nicholson [7]. In 2002, V. P. Camillo and D. D. Anderson [1] investigated commutative clean rings and obtained several important results. In [4] Han and Nicholson show that if A is a semiperfect ring, then A[Z2] i...
we say that a module $m$ is a emph{cms-module} if, for every cofinite submodule $n$ of $m$, there exist submodules $k$ and $k^{'}$ of $m$ such that $k$ is a supplement of $n$, and $k$, $k^{'}$ are mutual supplements in $m$. in this article, the various properties of cms-modules are given as a generalization of $oplus$-cofinitely supplemented modules. in particular, we prove tha...
We say that a module $M$ is a emph{cms-module} if, for every cofinite submodule $N$ of $M$, there exist submodules $K$ and $K^{'}$ of $M$ such that $K$ is a supplement of $N$, and $K$, $K^{'}$ are mutual supplements in $M$. In this article, the various properties of cms-modules are given as a generalization of $oplus$-cofinitely supplemented modules. In particular, we prove tha...
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