Symmetric form geometric constant related to isosceles orthogonality in Banach spaces

Fuente: arXiv
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Main Authors: Ni, Qichuan, Liu, Qi, Wang, Yuxin, Xia, Jinyu, Wang, Ranran
Format: Preprint
Published: 2025
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_version_ 1866912303830532096
author Ni, Qichuan
Liu, Qi
Wang, Yuxin
Xia, Jinyu
Wang, Ranran
author_facet Ni, Qichuan
Liu, Qi
Wang, Yuxin
Xia, Jinyu
Wang, Ranran
contents In this article, we introduce a novel geometric constant $L_X(t)$, which provides an equivalent definition of the von Neumann-Jordan constant from an orthogonal perspective. First, we present some fundamental properties of the constant $L_X(t)$ in Banach spaces, including its upper and lower bounds, as well as its convexity, non-increasing continuity. Next, we establish the identities of $L_X(t)$ and the function $γ_X(t)$, the von Neumann-Jordan constant, respectively. We also delve into the relationship between this novel constant and several renowned geometric constants (such as the James constant and the modulus of convexity). Furthermore, by utilizing the lower bound of this new constant, we characterize Hilbert spaces. Finally, based on these findings, we further investigate the connection between this novel constant and the geometric properties of Banach spaces, including uniformly non-square, uniformly normal structure, uniformly smooth, etc.
format Preprint
id arxiv_https___arxiv_org_abs_2504_00826
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Symmetric form geometric constant related to isosceles orthogonality in Banach spaces
Ni, Qichuan
Liu, Qi
Wang, Yuxin
Xia, Jinyu
Wang, Ranran
Functional Analysis
46B20, 46C15
F.2.2
In this article, we introduce a novel geometric constant $L_X(t)$, which provides an equivalent definition of the von Neumann-Jordan constant from an orthogonal perspective. First, we present some fundamental properties of the constant $L_X(t)$ in Banach spaces, including its upper and lower bounds, as well as its convexity, non-increasing continuity. Next, we establish the identities of $L_X(t)$ and the function $γ_X(t)$, the von Neumann-Jordan constant, respectively. We also delve into the relationship between this novel constant and several renowned geometric constants (such as the James constant and the modulus of convexity). Furthermore, by utilizing the lower bound of this new constant, we characterize Hilbert spaces. Finally, based on these findings, we further investigate the connection between this novel constant and the geometric properties of Banach spaces, including uniformly non-square, uniformly normal structure, uniformly smooth, etc.
title Symmetric form geometric constant related to isosceles orthogonality in Banach spaces
topic Functional Analysis
46B20, 46C15
F.2.2
url https://arxiv.org/abs/2504.00826