摘要
设R是任何环,L是R-模.若对任何平坦维数有限的模M,有Ext_R^1(M,L)=0,则L称为强余挠模.证明(F_∞,SC)是余挠理论当且仅当l.FFD(R)<∞,其中F_∞和SC分别表示平坦维数有限的模类和强余挠模类.还证明若w.gl.dim(R)<∞,则强余挠模是内射模.最后证明每一R-模是强余挠模当且仅当R是左完全环,且l.FFD(R)=0.
Let R be a ring and L an R-module. If Ext_R^1( M,L) = 0 for all R-module M with finite flat dimension,then L is called strongly cotorsion. In this paper,it is shown that( F_∞,SC) is a cotorsion theory if and only if l. FFD( R) ∞,where F∞and SC denote respectively the class of modules with finite flat dimension and the class of strongly cotorsion modules. It is also shown that if w.gl. dim( R) ∞,then all strongly cotorsion modules are injective. It is finally proved that every R-module is strongly cotorsion if and only if R is left perfect with l. FFD( R) = 0.
出处
《四川师范大学学报(自然科学版)》
CAS
北大核心
2016年第3期314-317,共4页
Journal of Sichuan Normal University(Natural Science)
基金
国家自然科学基金(11171240)
教育部博士点专项科研基金(20125134110002)
关键词
余挠模
强余挠模
平坦维数
左完全环
环的弱finitistic维数
cotorsion module
strongly cotorsion module
flat dimension
left perfect ring
weak finitistic dimension of a ring