An order-theoretic characterization of C*-algebras

Fuente: arXiv
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Main Author: Tiersma, Samuel
Format: Preprint
Published: 2026
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author Tiersma, Samuel
author_facet Tiersma, Samuel
contents We give an order-theoretic characterization of the essential image of the forgetful functor from the category of real/complex unital C*-algebras to the category of real/complex unital operator systems. It is based on the characterization of JB-algebras among the order unit spaces in terms of the existence of gauge-reversing bijections obtained by M. Roelands and the author in arXiv:2507.09526. To this end, we show that a unital operator system is completely order isomorphic to a C*-algebra if and only if each of its matrix spaces admits a compatible JB-algebra structure. As an application, we prove that for $n\ge 4$ the range of a unital n-positive projection on a unital real C*-algebra is unitally n-order isomorphic to a unital real C*-algebra, which is the analogue of a result proven for complex C*-algebras by Choi--Effros.
format Preprint
id arxiv_https___arxiv_org_abs_2604_16904
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle An order-theoretic characterization of C*-algebras
Tiersma, Samuel
Operator Algebras
46L07, 17C65, 46L05, 46L70
We give an order-theoretic characterization of the essential image of the forgetful functor from the category of real/complex unital C*-algebras to the category of real/complex unital operator systems. It is based on the characterization of JB-algebras among the order unit spaces in terms of the existence of gauge-reversing bijections obtained by M. Roelands and the author in arXiv:2507.09526. To this end, we show that a unital operator system is completely order isomorphic to a C*-algebra if and only if each of its matrix spaces admits a compatible JB-algebra structure. As an application, we prove that for $n\ge 4$ the range of a unital n-positive projection on a unital real C*-algebra is unitally n-order isomorphic to a unital real C*-algebra, which is the analogue of a result proven for complex C*-algebras by Choi--Effros.
title An order-theoretic characterization of C*-algebras
topic Operator Algebras
46L07, 17C65, 46L05, 46L70
url https://arxiv.org/abs/2604.16904