On the existence of Gorenstein injective covers
Abstract
For a locally finitely generated Grothendieck category, we characterise the Gorenstein injective covering property by several equivalent conditions, including closure under coproducts. To complete this characterisation, we construct a countable commutative Noetherian Cohen--Macaulay local ring of dimension one for which this property fails, answering negatively Iacob's question Question 1 whether character modules of Gorenstein injective modules over left Noetherian rings are Gorenstein flat. Using this characterisation, we prove that for Noetherian schemes the covering property is Zariski-local. Moreover, assuming that π’β(QCoh(X)) is a covering class, we establish compatible adjunctions and recollements for homotopy categories of injectives and totally acyclic injective complexes under open restriction. However, this property is not stalk-local: we construct a commutative Noetherian ring S such that π’β(Sp) forms a covering class for all prime ideals p, but π’β(S) do not form a covering class.
Related
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BibTeX
@misc{hua2026existence,
title = {{On the existence of Gorenstein injective covers}},
author = {Yuhui Hua and Shun-Jie Li and Chencheng Zhang},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.18620},
eprint = {2610.18620},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.18620},
note = {CC0},
}
RIS
TY - UNPB
TI - On the existence of Gorenstein injective covers
AU - Yuhui Hua
AU - Shun-Jie Li
AU - Chencheng Zhang
PY - 2026
DA - 2026/10/13
PB - arXiv
DO - 10.48550/arxiv.2610.18620
UR - https://arxiv.org/abs/2610.18620
AB - For a locally finitely generated Grothendieck category, we characterise the Gorenstein injective covering property by several equivalent conditions, including closure under coproducts. To complete this characterisation, we construct a countable commutative Noetherian Cohen--Macaulay local ring of dimension one for which this property fails, answering negatively Iacob's question Question 1 whether character modules of Gorenstein injective modules over left Noetherian rings are Gorenstein flat. Using this characterisation, we prove that for Noetherian schemes the covering property is Zariski-local. Moreover, assuming that π’β(QCoh(X)) is a covering class, we establish compatible adjunctions and recollements for homotopy categories of injectives and totally acyclic injective complexes under open restriction. However, this property is not stalk-local: we construct a commutative Noetherian ring S such that π’β(S_p) forms a covering class for all prime ideals p, but π’β(S) do not form a covering class.
ER -