Paper-folding models for the CAR algebra

Fuente: arXiv
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Autori principali: Kopsacheilis, Grigoris, Winter, Wilhelm
Natura: Preprint
Pubblicazione: 2025
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author Kopsacheilis, Grigoris
Winter, Wilhelm
author_facet Kopsacheilis, Grigoris
Winter, Wilhelm
contents We show that the CAR algebra admits a Cantor spectrum C*-diagonal that is not conjugate to the standard AF diagonal. We obtain this by classification theory of C*-algebras, and the diagonal arises by realising the CAR algebra as the crossed product of a free minimal action on the Cantor space, where the acting group is the product of a locally finite group with the infinite dihedral group. The main ingredient in the construction is a binary subshift associated to the well-known regular paper-folding sequence. Moreover, we show that the CAR algebra in fact admits countably many, pairwise non-conjugate, Cantor spectrum diagonals which are distinguished by the different values of their diagonal dimension, as defined by Li, Liao and the second named author.
format Preprint
id arxiv_https___arxiv_org_abs_2508_04837
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Paper-folding models for the CAR algebra
Kopsacheilis, Grigoris
Winter, Wilhelm
Operator Algebras
Dynamical Systems
Functional Analysis
We show that the CAR algebra admits a Cantor spectrum C*-diagonal that is not conjugate to the standard AF diagonal. We obtain this by classification theory of C*-algebras, and the diagonal arises by realising the CAR algebra as the crossed product of a free minimal action on the Cantor space, where the acting group is the product of a locally finite group with the infinite dihedral group. The main ingredient in the construction is a binary subshift associated to the well-known regular paper-folding sequence. Moreover, we show that the CAR algebra in fact admits countably many, pairwise non-conjugate, Cantor spectrum diagonals which are distinguished by the different values of their diagonal dimension, as defined by Li, Liao and the second named author.
title Paper-folding models for the CAR algebra
topic Operator Algebras
Dynamical Systems
Functional Analysis
url https://arxiv.org/abs/2508.04837