We first prove that if a monomorphism is a phantom envelope of a left R-module, then its
cokernel is pure-projective; if R is a left coherent ring and an epimorphism is an Ext Ext …

A morphism f: M→ N of left R-modules is called a phantom morphism if the induced
morphism for every (finitely presented) right R-module A. Similarly, a morphism g: M→ N of …

We study an R-module M in which every finitely generated submodule of M is a kernel of an
endomorphism of M. Such modules are called Co-epi-finite-retractable (CEFR). We also …

Abstract A left R-module M is said to be fp-injective if, for every monomorphism K→ L with K
and L finitely presented left R-modules, Hom (L, M)→ Hom (K, M) is an epimorphism. A right …

A module is called nilpotent-invariant if it is invariant under any nilpotent endomorphism of
its injective envelope [MT Koşan and TC Quynh, Nilpotent-invaraint modules and rings …

This paper extends many conclusions based on phantom envelopes and Ext-phantom
covers of modules, and we find that many important properties still hold after replacing …

In this paper, we investigate the notions of-projective,-injective, and-flat modules and give
some characterizations of these modules, where is a class of left modules. We prove that the …

We prove the following results for a ring R.(a) If C is a class of right R-modules closed under
direct summands and isomorphisms, then every right R-module has an epic C-envelope if …

Self-injective and PF endomorphism rings Page 1 ISRAEL JOURNAL OF MATHEMATICS, Vol.
58, No. 3, 1987 SELF-INJECTIVE AND PF ENDOMORPHISM RINGS BY JL GARCiA …

A submodule N of a module M is called S-closed (in M) if M/N is nonsingular. It is well-known
that the class Closed of short exact sequences determined by closed submodules is a …