Abstract
Let (X, Γ) be a free minimal dynamical system, where X is a compact separable Hausdorff space and Γ is a discrete amenable group. It is shown that, if (X, Γ) has a version of Rokhlin property (uniform Rokhlin property) and if C(X) ⋊ Γ has a Cuntz comparison on open sets, then the comparison radius of the crossed product C*-algebra C(X) ⋊ Γ is at most half of the mean topological dimension of (X, Γ).
These two conditions are shown to be satisfied if Γ = ℤ or if (X, Γ) is an extension of a free Cantor system and Γ has subexponential growth. The main tools being used are Cuntz comparison of diagonal elements of a subhomogeneous C*-algebra and small subgroupoids.
Similar content being viewed by others
References
N. P. Brown and N. Ozawa, C*-Algebras and Finite-Dimenisional Approximations, American Mathematical Society, Providence, RI, 2008.
L. O. Clark, Classifying the types of principal groupoid C*-algebras, J. Operator Theory 57 (2007), 251–266.
J. Cuntz, Dimension functions on simple C*-algebras, Math. Ann. 233 (1978), 145–153.
J. Dixmier, C*-Algebras, North-Holland, Amsterdam—New York—Oxford, 1977.
D. Dou, Minimal subshifts of arbitrary mean topological dimension, Discrete Contin. Dyn. Syst. 37 (2017), 1411–1424.
T. Downarowicz and D. Huczek, Dynamical quasitilings of amenable groups, Bull. Pol. Acad. Sci. Math. 66 (2018), 45–55.
T. Downarowicz and G. Zhang, The comparison property of amenable groups, arXiv:1712.05129 [math.DS].
E. G. Effros and F. Hahn, Locally Compact Transformation Groups and C*-Algebras, American Mathematical Society, Providence, RI, 1967.
G. A. Elliott, G. Gong and L. Li, On the classification of simple inductive limit C*-algebras. II. The isomorphism theorem, Invent. Math. 168 (2007), 249–320.
G. A. Elliott, G. Gong, H. Lin and Z. Niu, On the classification of simple amenable C*-algebras with finite decomposition rank, II, arXiv:1507.03437 [math.OA].
G. A. Elliott, G. Gong, H. Lin and Z. Niu, The classification of simple separable unital Z-stable locally ASH algebras, J. Funct. Anal. 12 (2017), 5307–5359.
G. A. Elliott and Z. Niu, On the radius of comparison of a commutative C*-algebra, Canad. Math. Bull. 56 (2013), 737–744.
G. A. Elliott and Z. Niu, All irrational extended rotation algebras are AF, Canad. J. Math. 67 (2015), 810–826.
G. A. Elliott and Z. Niu, On the classification of simple amenable C*-algebras with finite decomposition rank, in Operator Algebras and their Applications: A Tribute to Richard V. Kadison, American Mathematical Society, Providence, RI, 2016, pp. 117–125.
G. A. Elliott and Z. Niu, The C*-algebra of a minimal homeomorphism of zero mean dimension, Duke Math. J. 166 (2017), 3569–3594.
G. A. Elliott, Z. Niu, L. Santiago and A. Tikuisis, Decomposition rank of approximately subhomogeneous C*-algebras, Forum Math. 32 (2020), 827–889.
J. Giol and D. Kerr, Subshifts and perforation, J. Reine Angew. Math. 639 (2010), 107–119.
T. Giordano, I. F. Putnam and C. F. Skau, Topological orbit equivalence and C*-crossed products, J. Reine Angew. Math. 469 (1995), 51–111.
E. Glasner and B. Weiss, Weak orbit equivalence of Cantor minimal systems, Internat. J. Math. 6 (1995), 559–579.
G. Gong, On the classification of simple inductive limit C*-algebras. I. The reduction theorem, Doc. Math. 7 (2002), 255–461.
G. Gong, H. Lin and Z. Niu, Classification of finite simple amenable Z-stable C*-algebras, I. C*-algebras with generalized tracial rank one, C. R. Math. Acad. Sci. Soc. R. Can. 42 (2020), 63–450.
G. Gong, H. Lin and Z. Niu, Classification of finite simple amenable Z-stable C*-algebras, II. C*-algebras with rational generalized tracial rank one, C. R. Math. Acad. Sci. Soc. R. Can. 42 (2020), 451–539.
M. Gromov, Topological invariants of dynamical systems and spaces of holomorphic maps. I, Math. Phys. Anal. Geom. 2 (1999), 323–415.
Y. Gutman, Embedding ℤk-actions in cubical shifts and ℤk-symbolic extensions, Ergodic Theory Dynam. Systems 31 (2011), 383–403.
Y. Gutman, E. Lindenstrauss and M. Tsukamoto, Mean dimension of ℤk-actions, Geom. Funct. Anal. 26 (2016), 778–817.
U. Haagerup, Quasitraces on exact C*-algebras are traces, C. R. Math. Acad. Sci. Soc. R. Can. 36 (2014), 67–92.
R. H. Herman, I. F. Putnam and C. F. Skau, Ordered Bratteli diagrams, dimension groups and topological dynamics, Internat. J. Math. 3 (1992), 827–864.
I. Kaplansky, The structure of certain operator algebras, Trans. Amer. Math. Soc. 70 (1951), 219–255.
D. Kerr, Dimension, comparison, and almost finiteness, J. Eur. Math. Soc. (JEMS) 22 (2020), 3697–3745.
D. Kerr and G. Szabo, Almost finiteness and the small boundary property, Comm. Math. Phys. 374 (2020), 1–31.
Q. Lin, Analytic structure of the transformation group C*-algebra associated with minimal dynamical systems, preprint.
Q. Lin and N. C. Phillips, Direct limit decomposition for C*-algebras of minimal diffeomorphisms, in Operator Algebras and Applications, Mathematical Society of Japan, Tokyo, 2004, pp. 107–133.
E. Lindenstrauss, Mean dimension, small entropy factors and an embedding theorem, Inst. Hautes Etudes Sci. Publ. Math. 89 (2000), 227–262.
E. Lindenstrauss and B. Weiss, Mean topological dimension, Israel J. Math. 115 (2000), 1–24.
Z. Niu, Mean dimension and AH-algebras with diagonal maps, J. Funct. Anal. 266 (2014), 4938–4994.
Z. Niu, Comparison radius and mean topological dimension: ℤd-actions, arXiv:1906.09171 [math.OA].
Z. Niu, Z-stability of C(X) ⋊ Γ, Trans. Amer. Math. Soc. 374 (2021), 7525–7551.
N. C. Phillips, Recursive subhomogeneous algebras, Trans. Amer. Math. Soc. 359 (2007), 4595–4623.
N. C. Phillips, The C*-algebra of a minimal homeomorphism with finite mean dimension has finite radius of comparison, arXiv:1605.07976 [math.OA].
J. Renault, A Groupoid Approach to C*-Algebras, Springer, Berlin, 1980.
M. Rørdam, On the structure of simple C*-algebras tensored with a UHF-algebra. II, J. Funct. Anal. 107 (1992), 255–269.
G. Szabó, The Rokhlin dimension of topological ℤm-actions, Proc. Lond. Math. Soc. (3) 110 (2015), 673–694.
A. S. Toms, Flat dimension growth for C*-algebras, J. Funct. Anal. 238 (2006), 678–708.
A. S. Toms, Comparison theory and smooth minimal C*-dynamics, Comm. Math. Phys. 289 (2009), 401–433.
A. S. Toms, K-theoretic rigidity and slow dimension growth, Invent. Math. 183 (2011), 225–244.
A. S. Toms and W. Winter, Minimal dynamics and K-theoretic rigidity: Elliott’s conjecture, Geom. Funct. Anal. 23 (2013), 467–481.
D. P. Williams, Crossed Products of C*-Algebras, American Mathematical Society, Providence, RI, 2007.
G. Zeller-Meier, Produits croises d’une C*-algèbre par un groupe d’automorphismes, J. Math. Pures Appl. (9) 47 (1968), 101–239.
Author information
Authors and Affiliations
Corresponding author
Additional information
The research is partially supported by a Simons Collaboration Grant (Grant #317222) and partially supported by an NSF grant (DMS-1800882).
Rights and permissions
About this article
Cite this article
Niu, Z. Comparison radius and mean topological dimension: Rokhlin property, comparison of open sets, and subhomogeneous C*-algebras. JAMA 146, 595–672 (2022). https://doi.org/10.1007/s11854-022-0205-8
Received:
Revised:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s11854-022-0205-8