PreprintCC BY 4.0arXiv
A proper dg algebra which does not cogenerate
Abstract
Keller's strong form of the homological conjectures asserts: any finite dimensional algebra cogenerates its unbounded derived category of modules. Here we record an example of a (coconnective) dg algebra with finite dimensional cohomology, which does not cogenerate its module category, along with some related phenomena: a smooth dg category whose dualizing bimodule fails to be nondegenerate, and a nontrivial fully faithful left Calabi-Yau morphism. All examples and most proofs were produced by ChatGPT. In an appendix we explain the reason we were looking for such examples: their existence would follow from the existence of Weinstein symplectic manifolds which failed to satisfy Arnol'd's chord conjecture.
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BibTeX
@misc{hu2026proper,
title = {{A proper dg algebra which does not cogenerate}},
author = {Mingyuan Hu and Vivek Shende and Dinglong Wang},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.34193},
eprint = {2609.34193},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.34193},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - A proper dg algebra which does not cogenerate
AU - Mingyuan Hu
AU - Vivek Shende
AU - Dinglong Wang
PY - 2026
DA - 2026/09/28
PB - arXiv
DO - 10.48550/arxiv.2609.34193
UR - https://arxiv.org/abs/2609.34193
AB - Keller's strong form of the homological conjectures asserts: any finite dimensional algebra cogenerates its unbounded derived category of modules. Here we record an example of a (coconnective) dg algebra with finite dimensional cohomology, which does not cogenerate its module category, along with some related phenomena: a smooth dg category whose dualizing bimodule fails to be nondegenerate, and a nontrivial fully faithful left Calabi-Yau morphism. All examples and most proofs were produced by ChatGPT. In an appendix we explain the reason we were looking for such examples: their existence would follow from the existence of Weinstein symplectic manifolds which failed to satisfy Arnol'd's chord conjecture.
ER -