Envelopes, covers and semidualizing modules
Abstract
Given an R-module C and a class of R-modules 𝒟 over a commutative ring R, we investigate the relationship between the existence of 𝒟-envelopes (respectively, 𝒟-covers) and the existence of Hom(C,𝒟)-envelopes or C⊗𝒟-envelopes (respectively, Hom(C,𝒟)-covers or C⊗𝒟-covers) of modules. As a consequence, we characterize coherent rings, Noetherian rings, perfect rings and Artinian rings in terms of envelopes and covers by C-projective, C-flat, C-injective and C-FP-injective modules, where C is a semidualizing R-module.
Communicated by A. Facchini