Let R be a ring with identity element and M be a unitary left R-module. M is called quasi-
injective if every element in Hom^ Af, M) for any R-module N in M is extened to an element in …

Throughout, all rings R are associative with identity, and all inodules are unitary right R-
modules. By a class K of modules we inean K is a collection of nlodules such that K is closed …

For R a ring with identity, let ER= E (RR) denote the injective hull of RR and Λ its
endomorphism ring. We study the question of when there exists a ring structure on ER, or …

We develop a technique to construct finitely injective modules which are non-trivial, in the
sense that they are not direct sums of injective modules. As a consequence, we prove that a …

The concept of a module M being almost N-injective, where N is some module, was
introduced by Baba (1989). For a given module M, the class of modules N, for which M is …

Let R be an arbitrary ring and let (−)+= HomZ (−, Q/Z), where Z is the ring of integers and Q is
the ring of rational numbers. Let C be a subcategory of left R-modules and D a subcategory …

Pierce [3] has shown that over a commutative regular ring every finitely generated
submodule of an n-generated module is n-generated, and then has asked if this result holds …

Let R be a ring, X a class of left R‐modules, S the class of submodules of X, and Q the class
of quotient‐modules of X. It is shown that SQ is precovering (preenveloping) if and only if …

An example is given of a finitely generated module over a commutative ring whose
endomorphism ring does not have a classical ring of quotients. Vasconcelos [3] has shown …

Cukerman [2], Shanny [5], and Ware [7] have shown that a ring R is Artin semisimple if and
only if R has a nonfinitely generated free module with regular endomorphism ring. This …