Non-linear characterization of Jordan $*$-isomorphisms via maps on positive cones of $C^*$-algebras

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Auteurs principaux: Hatori, Osamu, Oi, Shiho
Format: Preprint
Publié: 2024
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author Hatori, Osamu
Oi, Shiho
author_facet Hatori, Osamu
Oi, Shiho
contents We study maps between positive definite or positive semidefinite cones of unital $C^*$-algebras. We describe surjective maps that preserve (1) the norm of the quotient or multiplication of elements; (2) the spectrum of the quotient or multiplication of elements; (3) the spectral seminorm of the quotient or multiplication of elements. These maps relate to the Jordan $*$-isomorphisms between the specified $C^*$-algebras. While a surjection between positive definite cones that preserves the norm of the quotient of elements may not be extended to a linear map between the underlying $C^*$-algebras, the other types of surjections can be extended to a Jordan $*$-isomorphism or a Jordan $*$-isomorphism followed by the implementation by a positive invertible element. We also study conditions for the centrality of positive invertible elements. We generalize "the corollary" regarding surjections between positive semidefinite cones of unital $C^*$-algebras. Applying it, we provide positive solutions to the problem posed by Molnár for general unital $C^*$-algebras.
format Preprint
id arxiv_https___arxiv_org_abs_2403_07341
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Non-linear characterization of Jordan $*$-isomorphisms via maps on positive cones of $C^*$-algebras
Hatori, Osamu
Oi, Shiho
Operator Algebras
Functional Analysis
We study maps between positive definite or positive semidefinite cones of unital $C^*$-algebras. We describe surjective maps that preserve (1) the norm of the quotient or multiplication of elements; (2) the spectrum of the quotient or multiplication of elements; (3) the spectral seminorm of the quotient or multiplication of elements. These maps relate to the Jordan $*$-isomorphisms between the specified $C^*$-algebras. While a surjection between positive definite cones that preserves the norm of the quotient of elements may not be extended to a linear map between the underlying $C^*$-algebras, the other types of surjections can be extended to a Jordan $*$-isomorphism or a Jordan $*$-isomorphism followed by the implementation by a positive invertible element. We also study conditions for the centrality of positive invertible elements. We generalize "the corollary" regarding surjections between positive semidefinite cones of unital $C^*$-algebras. Applying it, we provide positive solutions to the problem posed by Molnár for general unital $C^*$-algebras.
title Non-linear characterization of Jordan $*$-isomorphisms via maps on positive cones of $C^*$-algebras
topic Operator Algebras
Functional Analysis
url https://arxiv.org/abs/2403.07341