English

Salce's problem on cotorsion pairs is undecidable

Logic 2022-01-11 v3 Commutative Algebra Category Theory Rings and Algebras Representation Theory

Abstract

Salce \cite{MR565595} introduced the notion of a \emph{cotorsion pair} of classes of abelian groups, and asked whether every such pair is \emph{complete} (i.e., has enough injectives and projectives). We prove that it is consistent, relative to the consistency of Vop\v{e}nka's Principle (VP), that the answer is affirmative. Combined with a previous result of Eklof-Shelah \cite{MR2031314}, this shows that Salce's Problem is independent of the ZFC axioms (modulo the consistency of VP).

Cite

@article{arxiv.2103.06687,
  title  = {Salce's problem on cotorsion pairs is undecidable},
  author = {Sean Cox},
  journal= {arXiv preprint arXiv:2103.06687},
  year   = {2022}
}

Comments

To appear in Bulletin of the London Mathematical Society

R2 v1 2026-06-23T23:59:52.641Z