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Obstructions to the full Hao-Ng isomorphism
Abstract
We show that the Hao-Ng isomorphism for full crossed products fails to hold. More precisely, for a non-degenerate C*-correspondence X over a C*-algebra π and a generalized gauge action G curvearrowright X by a locally compact group G, we isolate three structural obstructions for the canonical commutation πͺXrtimes G β πͺXrtimes G between full crossed product and Cuntz-Pimsner C*-algebra. The first concerns hyperrigidity, the second concerns WEP of the coefficient C*-algebra π for trivial actions, and the third concerns the coincidence of full and reduced crossed products by the action of G on π.
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BibTeX
@misc{doron2026obstructions,
title = {{Obstructions to the full Hao-Ng isomorphism}},
author = {Adam Dor-On and Ian Thompson},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2608.31050},
eprint = {2608.31050},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2608.31050},
}
RIS
TY - UNPB
TI - Obstructions to the full Hao-Ng isomorphism
AU - Adam Dor-On
AU - Ian Thompson
PY - 2026
DA - 2026/09/07
PB - arXiv
DO - 10.48550/arxiv.2608.31050
UR - https://arxiv.org/abs/2608.31050
AB - We show that the Hao-Ng isomorphism for full crossed products fails to hold. More precisely, for a non-degenerate C^*-correspondence X over a C^*-algebra π and a generalized gauge action G curvearrowright X by a locally compact group G, we isolate three structural obstructions for the canonical commutation πͺ_Xrtimes G β
πͺ_Xrtimes G between full crossed product and Cuntz-Pimsner C^*-algebra. The first concerns hyperrigidity, the second concerns WEP of the coefficient C^*-algebra π for trivial actions, and the third concerns the coincidence of full and reduced crossed products by the action of G on π.
ER -