It is proved that a ring R is right perfect if and only if it is Σ-cotorsion as a right module over
itself. Several other conditions are shown to be equivalent. For example, that every pure …

Following, a ring R is called right almost-perfect if every flat right R-module is projective
relative to R. In this article, we continue the study of these rings and will find some new …

Chase has given several characterizations of a right coherent ring, among which are: every
direct product of copies of the ring is left-flat; and every finitely generated submodule of a …

Recently, Costa [4] introduced the concept of n-coherent rings. In this note we shall give
some further properties of n-coherent rings. Let R be a ring and na nonnegative integer …

In Bican et al., it is proved that all modules over an arbitrary ring have flat covers. In this
article, we shall study rings over which flat covers of finitely generated modules are …

R (finitely cogenerated) injective cogenerator in the category of right R-modules. The ring R
is a QF-ring if it is right PF and right (or left) artinian, and in this case R is two-sided PF and …

A ring R is called a left (right) SF-ring if all simple left (right) R-modules are flat. This concept
was introduced by VS Ramamurthi [a]. It is still an open question whether or not a left (or two …

Throughout, A represents an associative ring with identity and A-modules are unital. J, Z, Y
will denote respectively the Jacobson radical, the left singular ideal and the right singular …

Full article: Coherent rings and absolutely pure covers Skip to Main Content Taylor and Francis
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Let R by a right coherent ring and R-Mod denote the category of left R-modules. We show
that there is an abelian model structure on R-Mod whose cofibrant objects are precisely the …