A note on existence of envelopes and covers

J Chen, N Ding - Bulletin of the Australian Mathematical Society, 1996 - cambridge.org
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 …

Rings over which flat covers of finitely generated modules are projective

A Amini, M Ershad, H Sharif - Communications in Algebra, 2008 - Taylor & Francis
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 …

Absolutely s-Pure Modules and Neat-Flat Modules

E Büyükaşık, Y Durğun - Communications in Algebra, 2015 - Taylor & Francis
Let R be a ring with an identity element. We prove that R is right Kasch if and only if injective
hull of every simple right R-modules is neat-flat if and only if every absolutely pure right R …

The existence of flat covers

R Belshoff, EE Enochs, JZ Xu - Proceedings of the American Mathematical …, 1994 - ams.org
THE EXISTENCE OF FLAT COVERS flat, then <j> is called a flat cover of M if F' F —^— MF (b)
¡ \ F —^ M Page 1 proceedings OF THE AMERICAN MATHEMATICAL SOCIETY Volume 122 …

Rings whose modules are direct sums of extending modules

N Er - Proceedings of the American Mathematical Society, 2009 - ams.org
We prove that for a ring $ R $, the following are equivalent:(i) Every right $ R $-module is a
direct sum of extending modules, and (ii) $ R $ has finite type and right colocal type (ie …

When cyclic modules have Σ-injective hulls

C Faith - Communications in Algebra, 2003 - Taylor & Francis
A theorem of Cartan-Eilenberg (Cartan, H., Eilenberg, S.(1956). Homological Algebra.
Princeton: Princeton University Press, pp. 390.) states that a ring R is right Noetherian iff …

[HTML][HTML] Simple-direct-injective modules

V Camillo, Y Ibrahim, M Yousif, Y Zhou - Journal of algebra, 2014 - Elsevier
A module M over a ring is called simple-direct-injective if, whenever A and B are simple
submodules of M with A≅ B and B⊆⊕ M, we have A⊆⊕ M. Various basic properties of …

Exact envelopes of complexes

EE Enochs, GJR Rozas - Communications in Algebra, 1999 - Taylor & Francis
It is known that every complex of left R-modules has an exact cover. We consider the
question of finding R for which every complex of left i?-modules has an exact envelope. We …

Coherent rings and absolutely pure covers

G Dai, N Ding - Communications in Algebra, 2018 - Taylor & Francis
Full article: Coherent rings and absolutely pure covers Skip to Main Content Taylor and Francis
Online homepage Taylor and Francis Online homepage Log in | Register Cart 1.Home 2.All …

[PDF][PDF] On S-closed submodules

Y Durgun, S Ozdemir - J. Korean Math. Soc, 2017 - researchgate.net
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 …