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A non-trivially non-trivial automorphism at an inaccessible cardinal
Abstract
We show that, relative to the existence of an inaccessible cardinal, it is consistent that for an inaccessible cardinal κ, there is a non-trivial automorphism of 𝒫(κ)/fin whose restriction to 𝒫(β)/fin is induced by a bijection on β for every β<κ. This answers questions posed by Larson--McKenney, Shelah--Steprāns, and Veličković.
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BibTeX
@misc{poor2026nontrivially,
title = {{A non-trivially non-trivial automorphism at an inaccessible cardinal}},
author = {Márk Poór and Jing Zhang},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.08061},
eprint = {2609.08061},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.08061},
}
RIS
TY - UNPB
TI - A non-trivially non-trivial automorphism at an inaccessible cardinal
AU - Márk Poór
AU - Jing Zhang
PY - 2026
DA - 2026/09/07
PB - arXiv
DO - 10.48550/arxiv.2609.08061
UR - https://arxiv.org/abs/2609.08061
AB - We show that, relative to the existence of an inaccessible cardinal, it is consistent that for an inaccessible cardinal κ, there is a non-trivial automorphism of 𝒫(κ)/fin whose restriction to 𝒫(β)/fin is induced by a bijection on β for every β<κ. This answers questions posed by Larson--McKenney, Shelah--Steprāns, and Veličković.
ER -