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On diagonal actions of free group on the Cantor set

Operator Algebras 2019-12-25 v1 Dynamical Systems

Abstract

We study diagonal actions φ:F2F2×K\varphi:\mathbb{F}_2\curvearrowright\partial\mathbb{F}_2\times K on the Cantor set which are given by φa=a×α,φb=b×β\varphi_a=\partial_a\times\alpha,\varphi_b=\partial_b\times\beta. Under some restrictions on α,β\alpha,\beta we compute K(C(F2×K)rF2)K_*(C(\partial\mathbb{F}_2\times K)\rtimes_r\mathbb{F}_2). As an application in the case of α\alpha is Denjoy homeomorphism of the Cantor set and β=id\beta=id we will show that C(F2×K)rF2C(\partial\mathbb{F}_2\times K)\rtimes_r\mathbb{F}_2 is Kirchberg algebra with K(C(F2×K)rF2)=(Z,Z)K_*(C(\partial\mathbb{F}_2\times K)\rtimes_r\mathbb{F}_2)=(\mathbb{Z}^\infty,\mathbb{Z}^\infty). Also we will check that CC^*-crossed product by Denjoy homeomorphism on the Cantor set is CC^*-algebra generated by weighted shift, namely C(K)ZC(Tx)C(K)\rtimes\mathbb{Z}\cong C^*(T_x) where x{1,2}Zx\in \{1,2\}^\mathbb{Z} is two-sided Fibonacci sequence.

Keywords

Cite

@article{arxiv.1912.11134,
  title  = {On diagonal actions of free group on the Cantor set},
  author = {Anton Korchagin},
  journal= {arXiv preprint arXiv:1912.11134},
  year   = {2019}
}

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13 pages