English

Homomorphisms into a simple Z-stable C*-Algebras

Operator Algebras 2012-07-18 v3

Abstract

Let AA and BB be unital separable simple amenable \CA s which satisfy the Universal Coefficient Theorem. Suppose {that} AA and BB are Z\mathcal Z-stable and are of rationally tracial rank no more than one. We prove the following: Suppose that ϕ,ψ:AB\phi, \psi: A\to B are unital {monomorphisms}. There exists a sequence of unitaries {un}B\{u_n\}\subset B such that limnunϕ(a)un=ψ(a)\tforalaA, \lim_{n\to\infty} u_n^*\phi(a) u_n=\psi(a)\tforal a\in A, if and only if [ϕ]=[ψ]inKL(A,B),ϕ=ψ\andeqnϕ=ψ, [\phi]=[\psi]\,\,\,\text{in}\,\,\, KL(A,B), \phi_{\sharp}=\psi_{\sharp}\andeqn\phi^{\ddag}=\psi^{\ddag}, where ϕ,ψ:\aff(T(A))\aff(T(B))\phi_{\sharp}, \psi_{\sharp}: \aff(T(A))\to \aff(T(B)) and ϕ,ψ:U(A)/CU(A)U(B)/CU(B)\phi^{\ddag}, \psi^{\ddag}: U(A)/CU(A)\to U(B)/CU(B) are {the} induced maps and where T(A)T(A) and T(B)T(B) are tracial state spaces of AA and B,B, and CU(A)CU(A) and CU(B)CU(B) are closure of {commutator} subgroups of unitary groups of AA and B,B, respectively. We also show that this holds for some AH-algebras A.A. {Moreover, if κKL(A,B)\kappa\in KL(A,B) preserves the order and the identity, λ:\aff(\tr(A))\aff(\tr(B))\lambda: \aff(\tr(A))\to \aff(\tr(B)) is a continuous affine map and γ:U(A)/CU(A)U(B)/CU(B)\gamma: U(A)/CU(A)\to U(B)/CU(B) is a \hm\, which are compatible, we also show that there is a unital \hm\, ϕ:AB\phi: A\to B so that ([ϕ],ϕ,ϕ)=(κ,λ,γ),([\phi],\phi_{\sharp},\phi^{\ddag})=(\kappa, \lambda, \gamma), at least in the case that K1(A)K_1(A) is a free group,

Keywords

Cite

@article{arxiv.1003.1760,
  title  = {Homomorphisms into a simple Z-stable C*-Algebras},
  author = {Huaxin Lin and Zhuang Niu},
  journal= {arXiv preprint arXiv:1003.1760},
  year   = {2012}
}

Comments

The revision improves the original result. It is now 47 pages

R2 v1 2026-06-21T14:55:18.405Z