Let R be a ring, and let （F, C） be a cotorsion theory. In this article, the notion of F-perfect rings is introduced as a nontrial generalization of perfect rings and A-perfect rings. A ring R is said to be right dr-...Let R be a ring, and let （F, C） be a cotorsion theory. In this article, the notion of F-perfect rings is introduced as a nontrial generalization of perfect rings and A-perfect rings. A ring R is said to be right dr-perfect if F is projective relative to R for any F ∈ F. We give some characterizations of F-perfect rings. For example, we show that a ring R is right F-perfect if and only if F-covers of finitely generated modules are projective. Moreover, we define F-perfect modules and investigate some properties of them.展开更多
In this paper,the I-ring which satisfies almost descending chain conditions (shorten writting A. D. C. C) on principal left ideals is studied. Two main results are gaven: (1) I-ring which satisfies A. D.C. C on princi...In this paper,the I-ring which satisfies almost descending chain conditions (shorten writting A. D. C. C) on principal left ideals is studied. Two main results are gaven: (1) I-ring which satisfies A. D.C. C on principal left ideals is Boolen. (2) Ring with identity whose principal left ideals satisfy A. D. C. C and of which each element except identity is a left zero-divisor, is Boolean.These results generalize the results of [1],[2] and [3].展开更多
Let G and H be finite groups. It is proves that any ring isomorphism between character rings of G and H implies a perfect isometry between them, which is also a ring isomorphism.
In this paper, we introduce the concept of almost cotorsion modules. A module is called almost cotorsion if it is subisomorphic to its cotorsion envelope. Some characterizations of almost cotorsion modules are given. ...In this paper, we introduce the concept of almost cotorsion modules. A module is called almost cotorsion if it is subisomorphic to its cotorsion envelope. Some characterizations of almost cotorsion modules are given. It is also proved that every module is a direct summand of an almost cotorsion module. As an application, perfect rings are characterized in terms of almost cotorsion modules.展开更多
文摘Let R be a ring, and let （F, C） be a cotorsion theory. In this article, the notion of F-perfect rings is introduced as a nontrial generalization of perfect rings and A-perfect rings. A ring R is said to be right dr-perfect if F is projective relative to R for any F ∈ F. We give some characterizations of F-perfect rings. For example, we show that a ring R is right F-perfect if and only if F-covers of finitely generated modules are projective. Moreover, we define F-perfect modules and investigate some properties of them.
文摘In this paper,the I-ring which satisfies almost descending chain conditions (shorten writting A. D. C. C) on principal left ideals is studied. Two main results are gaven: (1) I-ring which satisfies A. D.C. C on principal left ideals is Boolen. (2) Ring with identity whose principal left ideals satisfy A. D. C. C and of which each element except identity is a left zero-divisor, is Boolean.These results generalize the results of [1],[2] and [3].
文摘Let G and H be finite groups. It is proves that any ring isomorphism between character rings of G and H implies a perfect isometry between them, which is also a ring isomorphism.
基金Specialized Research Fund (20050284015, 20030284033) for the Doctoral Program of Higher Education of China the Postdoctoral Research Fund (2005037713) of China Jiangsu Planned Projects for Postdoctoral Research Fund (0203003403) the Research Fund of Nanjing Institute of Technology of China
文摘In this paper, we introduce the concept of almost cotorsion modules. A module is called almost cotorsion if it is subisomorphic to its cotorsion envelope. Some characterizations of almost cotorsion modules are given. It is also proved that every module is a direct summand of an almost cotorsion module. As an application, perfect rings are characterized in terms of almost cotorsion modules.
