Sections and cones

Fuente: arXiv
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Autore principale: Shulman, Tatiana
Natura: Preprint
Pubblicazione: 2025
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author Shulman, Tatiana
author_facet Shulman, Tatiana
contents By Bartle-Graves theorem every surjective map between C*-algebras has a continuous section, and Loring proved that that there exists a continuous section of norm arbitrary close to 1. Here we prove that there exists a continuous section of norm exactly 1. This result is used in the second part of the paper which is devoted to properties of cone C*-algebras. It is proved that any $\ast$-homomorphism from the cone over a separable C*-algebra to a quotient C*-algebra always lifts to a contractive asymptotic homomorphism. As an application we give a short proof and strengthen the result of Forough-Gardella-Thomsen that states that any cpc (order zero) map has an asymptotically cpc (order zero, respectively) lift. As another application we give unified proofs of Voiculescu's result that cones are quasidiagonal and Brown-Carrion-White's result that all amenable traces on cones are quasidiagonal. We also prove that all hyperlinear traces on cones are MF.
format Preprint
id arxiv_https___arxiv_org_abs_2507_22783
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Sections and cones
Shulman, Tatiana
Operator Algebras
Functional Analysis
46L05
By Bartle-Graves theorem every surjective map between C*-algebras has a continuous section, and Loring proved that that there exists a continuous section of norm arbitrary close to 1. Here we prove that there exists a continuous section of norm exactly 1. This result is used in the second part of the paper which is devoted to properties of cone C*-algebras. It is proved that any $\ast$-homomorphism from the cone over a separable C*-algebra to a quotient C*-algebra always lifts to a contractive asymptotic homomorphism. As an application we give a short proof and strengthen the result of Forough-Gardella-Thomsen that states that any cpc (order zero) map has an asymptotically cpc (order zero, respectively) lift. As another application we give unified proofs of Voiculescu's result that cones are quasidiagonal and Brown-Carrion-White's result that all amenable traces on cones are quasidiagonal. We also prove that all hyperlinear traces on cones are MF.
title Sections and cones
topic Operator Algebras
Functional Analysis
46L05
url https://arxiv.org/abs/2507.22783