Character classification for stable simple AF algebras

Let AA be a stable simple AF algebra not isomorphic to K\mathbb{K}. Write TW(A)TW(A) for the tracial state space associated with AA, U(A)U_\to(A) for the relevant infinite-dimensional unitary group, and let Char(U(A))\operatorname{Char}(U_\to(A)) denote its characters. For τ,τTW(A)\tau,\tau'\in TW(A) and φHom(K0(A),Z)\varphi\in \operatorname{Hom}(K_0(A),\mathbb{Z}), let detφχτ,τ\mathrm{det}_\varphi\chi_{\tau,\tau'} be the corresponding determinant character. Character-classification conjecture.

exChar(U(A))={detφχτ,τ;  τ,τTW(A),  φHom(K0(A),Z)}.\operatorname{ex}\operatorname{Char}(U_\to(A))=\{\mathrm{det}_\varphi\chi_{\tau,\tau'};\;\tau,\tau'\in TW(A),\;\varphi\in \operatorname{Hom}(K_0(A),\mathbb{Z})\}.

This asks whether the classification of indecomposable characters proved under the finite-dimensionality assumption on TW(A)TW(A) remains valid without that assumption; the source presents it as a natural question, and no resolution is supplied here.

Sources & referencesView supporting material

Primary source

Takumi Enomoto and Masaki Izumi, “Indecomposable characters of infinite dimensional groups associated with operator algebras”, arXiv:1308.6329 (2013).

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