Tilting Torsion-Free Classes in the Category of Comodules.

A well-known Assem–Smal ϕ theorem on tilting modules plays an important role in tilting theory. In this paper, we prove that a version of Assem–Smal ϕ theorem still holds in the category of comodules. Following this result, we characterize the tilting torsion-free classes in the category of comodules using the precover theory. [ABSTRACT FROM AUTHOR]