This is the second revised edition of an introduction to contemporary relative homological
algebra. It supplies important material essential to understand topics in algebra, algebraic …

A module is said to be copure injective if it is injective with respect to all modules A⊂ B with
B/A injective. We first characterize submodules that have the extension property with respect …

We prove that (a) if R is left coherent, then a finitely presented right R–module M is copure
flat if and only if M is a cokernel of a flat preen-velope (b) if R is a ring and na nonnegative …

We study C-covers in the context of Grothendieck categories. Namely, we analyse when a
functor between two Grothendieck categories preserves or reflects C-covers. We apply our …

R will denote a left noetherian ring and all modules are unitary. Since R is left noetherian,
we can construct not necessarily acyclic complexes of a left R-module and a right K-module …

Given a precovering (also called contravariantly finite) class F there are three natural
approaches to a homological dimension with respect to F: One based on Ext functors …

The subject of relative homological algebra was introduced by S. Eilenberg and JC Moore in
their 1965 AMS Memoir 'Foundations of Relative Homological Algebra'. We now have in …

If R is left noetherian and M is a left R-module, then we can construct a complex called an
injective resolvent of M using injective precovers. Likewise, if R is left coherent and M is a …

1. Introduction. The grade of a module M (see [11]) may be considered as the least
nonnegative integer n such that Ext n (M, P)+ 0 for some projective module P. We can …

On Gorenstein rings Page 1 Math. Z. 197, 119-122 (1988) Mathematische Zeitschrift 9
Springer-Verlag 1988 On Gorenstein Rings Overtoun MG Jenda Department of Mathematics …