Precovers and preenvelopes by phantom and Ext-phantom morphisms

L Mao - Communications in Algebra, 2016 - Taylor & Francis
A morphism f: M→ N of left R-modules is called a phantom morphism if the induced
morphism for every (finitely presented) right R-module A. Similarly, a morphism g: M→ N of …

Precovers and Preenvelopes by Phantom and Ext-Phantom Morphisms

L Mao - Communications in Algebra, 2016 - ingentaconnect.com
A morphism f: M→ N of left R-modules is called a phantom morphism if the induced
morphism for every (finitely presented) right R-module A. Similarly, a morphism g: M→ N of …