f-投射与f-内射模

摘要

Let R be a ring.A right R-module M is called f-projective if Ext1(M,N) = 0for any f-injective right R-module N.We prove that (F-proj,F-inj) is a complete cotorsion theory,where F-proj (F-inj) denotes the class of all f-projective (f-injective) right R-modules.Semihereditary rings,von Neumann regular rings and coherent rings are characterized in terms of f-projective modules and f-injective modules.