Octonionic isometric isomorphisms and partial isometry

Fuente: arXiv
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Autori principali: Huo, Qinghai, Ren, Guangbin, Xu, Zhenghua
Natura: Preprint
Pubblicazione: 2026
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author Huo, Qinghai
Ren, Guangbin
Xu, Zhenghua
author_facet Huo, Qinghai
Ren, Guangbin
Xu, Zhenghua
contents Very recently, two new notions of para-linear mappings and weak associative orthonormal bases were introduced in octonionic functional analysis, which have been proved to be powerful in formulating the basic theory, such as the Riesz representation theorem and the Parseval theorem. In this article, we continue exploring more properties of these two concepts and initiate the study of octonionic para-linear isometric operators. Surprisingly, it is proven that the condition of the para-linear operator on a Hilbert octonionic bimodule being an isometric isomorphism is equivalent to it mapping any associative orthonormal basis to a weak associative orthonormal basis, which implies also that an octonionic matrix is an isometry if and only if the system of its row vectors is a weak associative orthonormal basis. Furthermore, we introduce the concept of para-linear partial isometric operators and establish the aforementioned analogue in this new setting. Based on these facts, we can provide naturally a new viewpoint of James questions by modifying the definition of octonionic Stiefel space.
format Preprint
id arxiv_https___arxiv_org_abs_2605_07226
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Octonionic isometric isomorphisms and partial isometry
Huo, Qinghai
Ren, Guangbin
Xu, Zhenghua
Functional Analysis
Primary 17A35, secondary 46S10
Very recently, two new notions of para-linear mappings and weak associative orthonormal bases were introduced in octonionic functional analysis, which have been proved to be powerful in formulating the basic theory, such as the Riesz representation theorem and the Parseval theorem. In this article, we continue exploring more properties of these two concepts and initiate the study of octonionic para-linear isometric operators. Surprisingly, it is proven that the condition of the para-linear operator on a Hilbert octonionic bimodule being an isometric isomorphism is equivalent to it mapping any associative orthonormal basis to a weak associative orthonormal basis, which implies also that an octonionic matrix is an isometry if and only if the system of its row vectors is a weak associative orthonormal basis. Furthermore, we introduce the concept of para-linear partial isometric operators and establish the aforementioned analogue in this new setting. Based on these facts, we can provide naturally a new viewpoint of James questions by modifying the definition of octonionic Stiefel space.
title Octonionic isometric isomorphisms and partial isometry
topic Functional Analysis
Primary 17A35, secondary 46S10
url https://arxiv.org/abs/2605.07226