English

Cotorsion pairs and Enochs Conjecture for object ideals

Category Theory 2024-12-10 v1

Abstract

Let I\mathcal{I} and J\mathcal{J} be object ideals in an exact category (A;E)(\mathcal{A}; \mathcal{E}). It is proved that (I,J)(\mathcal{I},\mathcal{J}) is a perfect ideal cotorsion pair if and only if (Ob(I),Ob(J))({\rm Ob}(\mathcal{I}),{\rm Ob}(\mathcal{J})) is a perfect cotorsion pair, where Ob(I){\rm Ob}(\mathcal{I}) and Ob(J){\rm Ob}(\mathcal{J}) is the objects of I\mathcal{I} and J\mathcal{J}, respectively. If in addition (A;E)(\mathcal{A}; \mathcal{E}) has enough projective objects and injective objects, and J\mathcal{J} is enveloping, then (I,J)(\mathcal{I},\mathcal{J}) is a complete ideal cotorsion pair if and only if (Ob(I),Ob(J))({\rm Ob}(\mathcal{I}),{\rm Ob}(\mathcal{J})) is a complete cotorsion pair. This gives a partial answer to the question posed by Fu, Guil Asensio, Herzog and Torrecillas. Moreover, for any object ideal I\mathcal{I} in the category of left RR-modules, it is proved that I\mathcal{I} satisfies Enochs Conjecture if and only if Ob(I){\rm Ob}(\mathcal{I}) satisfies Enochs Conjecture. Applications are given to projective morphisms and ideal cotorsion pairs (I,J)(\mathcal{I},\mathcal{J}) of object ideals under certain conditions.

Cite

@article{arxiv.2412.05519,
  title  = {Cotorsion pairs and Enochs Conjecture for object ideals},
  author = {Dandan Sun and Qikai Wang and Haiyan Zhu},
  journal= {arXiv preprint arXiv:2412.05519},
  year   = {2024}
}
R2 v1 2026-06-28T20:26:23.202Z