On injective dimension of the conormal module
Abstract
Let Q be a Gorenstein local ring, let I be a proper ideal of Q, and set R=Q/I. We investigate when finite injective dimension of the conormal module I/I2 forces I to be generated by a regular sequence. We prove this implication for every ideal in the linkage class of a complete intersection. When Q is regular, we also establish it under several numerical conditions in terms of the number of generators of I and the type of R. For normal domain quotients, we show that finite injective dimension of I/I2 forces (ht(I)+1)[ωR]=0 in Cl(R), yielding the desired conclusion when the divisor class group is torsionfree. In the graded setting, we further prove the implication for all monomial ideals in polynomial rings. We also obtain a converse to Kunz's description of the first Koszul homology of an almost complete intersection.
Related
- Finitistic injective dimension exceeding finitistic projective dimension for a commutative ring
- Perfect closure detects injective dimension
- Normality of closures of conormal bundles to Schubert cells for GLn
- Conormal Rank of Subvarieties of Grassmannians
- On Open Borel Orbits in Conormal Bundles to Schubert Cells
BibTeX
@misc{gheibi2026injective,
title = {{On injective dimension of the conormal module}},
author = {Mohsen Gheibi and Kaito Kimura},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.04031},
eprint = {2610.04031},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.04031},
}
RIS
TY - UNPB
TI - On injective dimension of the conormal module
AU - Mohsen Gheibi
AU - Kaito Kimura
PY - 2026
DA - 2026/10/08
PB - arXiv
DO - 10.48550/arxiv.2610.04031
UR - https://arxiv.org/abs/2610.04031
AB - Let Q be a Gorenstein local ring, let I be a proper ideal of Q, and set R=Q/I. We investigate when finite injective dimension of the conormal module I/I^2 forces I to be generated by a regular sequence. We prove this implication for every ideal in the linkage class of a complete intersection. When Q is regular, we also establish it under several numerical conditions in terms of the number of generators of I and the type of R. For normal domain quotients, we show that finite injective dimension of I/I^2 forces (ht(I)+1)[ω_R]=0 in Cl(R), yielding the desired conclusion when the divisor class group is torsionfree. In the graded setting, we further prove the implication for all monomial ideals in polynomial rings. We also obtain a converse to Kunz's description of the first Koszul homology of an almost complete intersection.
ER -