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For an endomorphism of a ring , the endomorphism is called left semicommutative if implies ( )semicommutative endomorphism of . In this paper, varios results of semicommutative rings are extended to left −semicommutative rings, bir halka ve da nin bir endomorfizması olmak üzere eğer, , ∈ için = 0 olması ( )= 0 olmasını gerektiriyor ise, bu durumda endomorfizmasına soldan yarıdeğişmelidir denir. Eğer bir halkasının soldan yarıdeğişmeli bir endomorfizması varsa, bu durumda halkasına soldan −yarıdeğişmeli halka denir. Bu çalışmada yarıdeğişmeli halkalar için bilinen bir çok sonuç soldan −yarıdeğişmeli halkalara genelleştirilecektir

This paper introduces and studies (X,Y)-Gorenstein projective and injective modules, which are a generalization of Enochs' Gorenstein projective and injective modules, respectively. Our main aim is to investigate the relations among various (X,Y)-Gorenstein projective modules.

In this paper, we introduce and study V -Gorenstein at modules and show the stability of the category of V -Gorenstein at modules. We investigate the existence of V -Gorenstein at covers and V -Gorenstein at preenvelopes for any left R -module. Also we prove that ( V - GF ;V - GF ? ) is a perfect hereditary cotorsion pair in B l ( R) , where V - GF stands the class of V -Gorenstein at left R -modules and B l ( R) is the left Bass class. Some applications are given.

In this paper, we introduce and study Ext-strongly Gorenstein projective modules. We prove that the class of Ext-strongly Gorenstein projective modules is projective resolving. Moreover, we consider Ext-strongly Gorenstein projective precovers.

In this paper we have obtained the following results for a differential ring (associative or nonassociative): (1) For a differential ring ({\cal D}-ring) we introduce definitions of a {\cal D}-prime {\cal D}-ideal, {\cal D}-semiprime {\cal D}-ideal and a strongly {\cal D}-nilpotent element. We define the {\cal D}-prime radical as the intersection of all {\cal D}-prime {\cal D}-ideals. For any {\cal D}-ring the {\cal D}-prime radical, the intersection of all {\cal D}-semiprime {\cal D}-semiprime {\cal D}-ideals and the set of all strongly {\cal D}-nilpotent elements are equal. (2) For a {\cal D}-ring we introduce a definition of an s-nilpotent {\cal D}-ideal. If a {\cal D}-ring satisfies the ascending chain condition for {\cal D}-ideals then its {\cal D}-prime radical is s-nilpotent. (3) Let {\cal Q} be a field of rational numbers. If d is a differentiation of a {\cal Q}-algebra R with 1 then d (Pr.rad(R))\subseteq Pr. rad(R). (4) Let K be a differential ring. Then every radical {\cal D}-ideal of K is an intersection of {\cal D}-prime {\cal D}-ideals.

In tins paper, we give some characterizations of modules M over a ring R such that every submodule has a unique closure relative to a hereditary torsion theory on Mod- R by using the concept of tau-closed submodule which was studied in [2]. We compare UC and tau-UC modules and examine the relationships between them. We also give some examples of tau-UC and UC modules and submodules which have a unique tau-closure and unique closure.

Let R be a commutative ring with a unit and M an R-module. In this paper we give a comparison between the F-closure in M of an R-submodule having a minimal extension and the closure of this minimal extension for the same Gabriel topology defined on the ring R. If J(R) \in F we prove that both closures are the same. Moreover, if R is Artinian or semi-simple then the converse also holds.

In this paper, we discuss the Bass class and the Auslander class with respect to a semidualizing module over an associative ring. Let SCR be a semidualizing module, we proved that the Bass class BC (R) is a right orthogonal subcategory of some right R-module; and that the Auslander class AC (S) is a left orthogonal subcategory of the character module of some left S-module. As an application, we introduce the notion of the minimal semidualizing module, and get a one to one correspondence between the isomorphism classes of minimal semidualizing R-modules and maximal classes among coresolving preenvelope classes of Mod R with the same Ext-projective generators in gen* R.

In this paper, we introduce some characterizations for augmented graded rings in special cases.

Let G be a multiplicative group with identity e, and let R be an associative G-graded ring with unity 1. In this paper we study the augmented graded Noetherian modules and try to give some relationships between the Noetherian modules in the category R-Agr and the Noetherian modules in the category Re-gr.