In a pushout-pullback diagram, which consists of four morphisms f ： A → B, g ： A → C, α ： C → D and β ： B → D, we give some relations among the covers of these four modules. If ker f∈I（ ）, then g ： A → ...In a pushout-pullback diagram, which consists of four morphisms f ： A → B, g ： A → C, α ： C → D and β ： B → D, we give some relations among the covers of these four modules. If ker f∈I（ ）, then g ： A → C is -covering if and only if ： B → D is -covering. If every module has an -precover and kerf E I（ ）, then A and C have isomorphic -precovers if and only if B and D have isomorphic -precovers.展开更多
除环上有零对象的矩阵范畴是Abel范畴,在这个范畴中,解齐次线性方程组( A, B )X = A0(或者X = 0)与求态射{A,B}的推出(或者求态射{A,B}的拉回)有着密切的关系.讨 B ...除环上有零对象的矩阵范畴是Abel范畴,在这个范畴中,解齐次线性方程组( A, B )X = A0(或者X = 0)与求态射{A,B}的推出(或者求态射{A,B}的拉回)有着密切的关系.讨 B A论除环上齐次线性方程组( A, B )X = 0和X = 0;研究除环上有关分块矩阵之间的关系, B得到了一些关于分块矩阵与其中子矩阵的秩的有关公式.展开更多
基金Supported by the Natural Science Foundation of Fujian Province (Grant No. 2009J01003)the Foundation of Fujian Normal University (Grant No. 2008100209)partially by the Open Funds of Key Lab of Fujian Province University Network Security and Cryptology (Grant No. 09A004)
文摘In a pushout-pullback diagram, which consists of four morphisms f ： A → B, g ： A → C, α ： C → D and β ： B → D, we give some relations among the covers of these four modules. If ker f∈I（ ）, then g ： A → C is -covering if and only if ： B → D is -covering. If every module has an -precover and kerf E I（ ）, then A and C have isomorphic -precovers if and only if B and D have isomorphic -precovers.
文摘除环上有零对象的矩阵范畴是Abel范畴,在这个范畴中,解齐次线性方程组( A, B )X = A0(或者X = 0)与求态射{A,B}的推出(或者求态射{A,B}的拉回)有着密切的关系.讨 B A论除环上齐次线性方程组( A, B )X = 0和X = 0;研究除环上有关分块矩阵之间的关系, B得到了一些关于分块矩阵与其中子矩阵的秩的有关公式.
