206 research outputs found

    Homomorphisms from AH-algebras

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    Let CC be a general unital AH-algebra and let AA be a unital simple Cβˆ—C^*-algebra with tracial rank at most one. Suppose that Ο•,ψ:Cβ†’A\phi, \psi: C\to A are two unital monomorphisms. We show that Ο•\phi and ψ\psi are approximately unitarily equivalent if and only if \beq[\phi]&=&[\psi] {\rm in} KL(C,A), \phi_{\sharp}&=&\psi_{\sharp}\tand \phi^{\dag}&=&\psi^{\dag}, \eneq where Ο•β™―\phi_{\sharp} and Οˆβ™―\psi_{\sharp} are continuous affine maps from tracial state space T(A)T(A) of AA to faithful tracial state space Tf(C)T_{\rm f}(C) of CC induced by Ο•\phi and ψ,\psi, respectively, and ϕ‑\phi^{\ddag} and Οˆβ€‘\psi^{\ddag} are induced homomorphisms from K1(C)K_1(C) into \Aff(T(A))/\bar{\rho_A(K_0(A))}, where \Aff(T(A)) is the space of all real affine continuous functions on T(A)T(A) and ρA(K0(A))Λ‰\bar{\rho_A(K_0(A))} is the closure of the image of K0(A)K_0(A) in the affine space \Aff(T(A)). In particular, the above holds for C=C(X),C=C(X), the algebra of continuous functions on a compact metric space. An approximate version of this is also obtained. We also show that, given a triple of compatible elements κ∈KLe(C,A)++,\kappa\in KL_e(C,A)^{++}, an affine map Ξ³:T(C)β†’Tf(C)\gamma: T(C)\to T_{\rm f}(C) and a \hm \af: K_1(C)\to \Aff(T(A))/\bar{\rho_A(K_0(A))}, there exists a unital monomorphism Ο•:Cβ†’A\phi: C\to A such that [h]=ΞΊ,[h]=\kappa, hβ™―=Ξ³h_{\sharp}=\gamma and $\phi^{\dag}=\af.
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