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The Borel complexity of conjugacy for Cantor minimal systems
Abstract
We prove that conjugacy of minimal homeomorphisms of the Cantor space is Borel bireducible with isomorphism of countable graphs, answering the Cantor minimal case of a question of Foreman. We obtain the lower bound by encoding countably based profinite groups. Finite quotient homomorphisms are represented by factor maps between a common family of minimal subshifts. Amalgamation makes the resulting inverse limit independent, up to conjugacy, of the quotient presentation. Conversely, finite-stage factorization recovers the group from any conjugacy of these inverse limits.
Related
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BibTeX
@misc{dai2026borel,
title = {{The Borel complexity of conjugacy for Cantor minimal systems}},
author = {Xinan Dai and Wenhao Deng and Yingdong Shi and Tailin Wu and Yuchen Yang},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.12031},
eprint = {2609.12031},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.12031},
}
RIS
TY - UNPB
TI - The Borel complexity of conjugacy for Cantor minimal systems
AU - Xinan Dai
AU - Wenhao Deng
AU - Yingdong Shi
AU - Tailin Wu
AU - Yuchen Yang
PY - 2026
DA - 2026/09/10
PB - arXiv
DO - 10.48550/arxiv.2609.12031
UR - https://arxiv.org/abs/2609.12031
AB - We prove that conjugacy of minimal homeomorphisms of the Cantor space is Borel bireducible with isomorphism of countable graphs, answering the Cantor minimal case of a question of Foreman. We obtain the lower bound by encoding countably based profinite groups. Finite quotient homomorphisms are represented by factor maps between a common family of minimal subshifts. Amalgamation makes the resulting inverse limit independent, up to conjugacy, of the quotient presentation. Conversely, finite-stage factorization recovers the group from any conjugacy of these inverse limits.
ER -