module M is a direct injective module for each monomorphism f: N→A(N is a direct summand of M,A is any submodule of M and),and the mapping Hom(f, M):Hom(A,M)→Hom( N,M) surjective; if is a direct injective module, then Mα so is Mα.
module M is a direct injective module for each monomorphism f: N→A(N is a direct summand of M,A is any submodule of M and),and the mapping Hom(f, M):Hom(A,M)→Hom( N,M) surjective; if is a direct injective module, then Mα so is Mα.
模M为直内射模对每个单同态f：N→A（N为M的直和顶，A为M的包含N的任意子模）有Hom（f，M）：Hom（A，M）→Hom（N，M）是满同态。