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 …

We study these rings with every minimal left ideal being a projective, direct summand and ap–
injective module, respectively. Some characterizations of these rings are given, and the …

A ring R is called a left APP-ring if the left annihilator lR (Ra) is pure as a left ideal of R for
every a∈ R; R is called (left principally) quasi-Baer if the left annihilator of every (principal) …

A ring R with unity is called right (left) self injective if the right (left) R-module R is injective
[7]. The purpose of this note is to prove the following: Let R be a prime ring with a maximal …

Let R be an associate ring with identity. A right R-module M is called mininjective if every
homomorphism from a simple right ideal of R to M can be extended to R. We now extend this …

A ring R is called left max-coherent provided that every maximal left ideal is finitely
presented. MI (resp. MF) denotes the class of all max-injective left R-modules (resp. all max …

Let R be a ring. Recall that a left R-module M is coherent if every finitely generated
submodule of M is finitely presented. R is a left coherent ring if the left R-module RR is …

We call a right module weakly neat-flat if is surjective for any epimorphism and any simple
right ideal. A left module is called weakly absolutely s-pure if is monic, for any …

Publisher Summary This chapter describes the Betti numbes and reflexive modules. A quasi-
Frobenius (QF) ring R may be described as a ring with the property that all of its modules are …