If R is a ring without zero divisors then it is shown that any torsion-free quasi-projective left R-
module A is projective provided A is finitely generated or A is “big”. It is proved that the …

Endomorphism rings of projective and quasiprojective modules (and in particular the
problem of finding conditions on a module for its endomorphism ring to have a certain …

In this paper $ R $ denotes an associative ring with an identity, and all modules are unital
left $ R $-modules. It is shown that the existence of a quasi-projective cover for each module …

A module M over a ring R is κ-projective, κ a cardinal, if M is projective relative to all exact
sequence of R-modules 0→ A→ B→ C→ 0 such that C has a generating set of cardinality …

A module M is said to be weakly N-projective if it has a projective cover π: P (M)↠ M and for
each homomorphism: P (M)→ N there exists an epimorphism σ: P (M)↠ M such that (kerσ) …

Recently,]~. DE ROBERT has considered the dual concepts of relative projectivity and
relative injectivity that extend the notions of quasi-projective and quasi-injective modules …

The authors have studied some structures in categories of completely indecomposable
modules in [5],[6] and [7], respectively. Furthermore, one of the authors has given some …

We characterize semiperfect modules? semiperfect rings, and perfect rings using locally
projective covers and generalized locally projective covers, where locally projective …

Introduction and notation. Throughout this paper all rings are associative rings with identity
and all modules are unitary left modules. An R-module M is quasi-injective in case HomR …

The main results determine the Goldie dimension of superfluous submodules of semiprime
left Goldie rings and apply this to the study of quasiprojective covers of torsion free modules …