English

Maximum deconstructibility in module categories

Representation Theory 2021-09-24 v7 Commutative Algebra Logic Rings and Algebras

Abstract

We prove that Vop\v{e}nka's Principle implies that for every class X\mathfrak{X} of modules over any ring, the class of \textbf{X\boldsymbol{\mathfrak{X}}-Gorenstein Projective modules} (\textbf{X\boldsymbol{\mathfrak{X}}-GP\boldsymbol{\mathcal{GP}}}) is a special precovering class. In particular, it is not possible to prove (unless Vop\v{e}nka's Principle is inconsistent) that there is a ring over which the \textbf{Ding Projectives} (DP\boldsymbol{\mathcal{DP}}) or the \textbf{Gorenstein Projectives} (GP\boldsymbol{\mathcal{GP}}) do not form a precovering class (\v{S}aroch previously obtained this result for the class GP\mathcal{GP}, using different methods). The key innovation is a new "top-down" characterization of \emph{deconstructibility}, which is a well-known sufficient condition for a class to be precovering. We also prove that Vop\v{e}nka's Principle implies, in some sense, the maximum possible amount of deconstructibility in module categories.

Keywords

Cite

@article{arxiv.2012.11084,
  title  = {Maximum deconstructibility in module categories},
  author = {Sean Cox},
  journal= {arXiv preprint arXiv:2012.11084},
  year   = {2021}
}

Comments

accepted version

R2 v1 2026-06-23T21:06:54.598Z