A ring R is called left P-coherent in case each principal left ideal of R is finitely presented. A
left R-module M (resp. right R-module N) is called D-injective (resp. D-flat) if Ext1 (G, M)= 0 …

Let R be any ring. A right R-module M is called n-copure projective if Ext1 (M, N)= 0 for any
right R-module N with fd (N)≤ n, and M is said to be strongly copure projective if Ext i (M, F) …

We study the existence of covers and envelopes by some special functors on the category of
finitely presented modules. As an application, we characterize some important rings using …

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 …

Let R be a left coherent ring. We first prove that a right R-module M is strongly copure flat if
and only if Ext i (M, C)= 0 for all flat cotorsion right R-modules C and i≥ 1. Then we define …

We establish equivalent conditions under which every object in an Abelian category has a
monic X-cover and an epic X-envelope respectively, when X is a class of objects closed …

In this paper, we introduce the concepts of Gorenstein FI-injective and Gorenstein FI-flat
modules and we are concerned with the stability of the class of Gorenstein FI-flat modules …

In this paper, we give some characterizations of FP-grinjective R-modules and graded right
R-modules of FP-gr-injective dimension at most n. We study the existence of FP-gr-injective …

本文研究了形式三角矩阵环上的Gorenstein FI-内射模. 设是形式三角矩阵环, 其中A, B 是环, U
是(B, A)-双模. 在一定条件下证明了若是Gorenstein FI-内射左T-模, 则M 2 是Gorenstein FI …

We investigate purities determined by classes of finitely presented modules including the
correspondence between purities for left and right modules. We show some cases where …