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arXiv 2610.13360math.FA
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巴拿赫空间、伯克霍夫-詹姆斯正交性、詹姆斯常数、冯·诺依曼-约当常数

An Improved Inequality between the von Neumann-Jordan and James Constants

School of Mathematics and Statistics, Anqing Normal University(安庆师范大学数学与统计学院)

Zhiyao Fang, Qi Liu

AI总结:

该研究针对巴拿赫空间中冯·诺依曼-约当常数与詹姆斯常数的比较问题,将经典不等式改进为涉及伯克霍夫-詹姆斯正交詹姆斯常数的形式,采用最优距离椭圆和交替接触方向完成证明。

摘要:

我们对Alonso、Martín和Papini[Studia Math. 188 (2008), 135--150]提出的关于冯·诺依曼-约当常数与詹姆斯常数比较的问题给出了更深入的解答。Takahashi和Kato[J. Math. Anal. Appl. 359 (2009), 602--609]、Wang[Proc. Amer. Math. Soc. 138 (2010), 695--701]以及Yang和Li[Appl. Math. Lett. 23 (2010), 277--281]建立了冯·诺依曼-约当常数与詹姆斯常数之间的经典不等式$\text{C}_{\text{NJ}}(X)\text{≤}J(X)$,Kato和Takahashi[Rend. Circ. Mat. Palermo (2) Suppl. 82 (2010), 75--91]则得到了相关的精确估计。我们将该不等式改进为$\text{C}_{\text{NJ}}(X)\text{≤}J_{\text{B}}(X)$,其中$J_{\text{B}}(X)$是Baronti和Papini[Constr. Math. Anal. 5 (2022), 37--45]引入的伯克霍夫-詹姆斯正交詹姆斯常数。我们的证明采用了最优距离椭圆和交替接触方向。

英文摘要:

We provide a strengthened answer to the questions posed by Alonso, Martín, and Papini [Studia Math. 188 (2008), 135--150] concerning the comparison between the von Neumann--Jordan and James constants . The classical inequality $\CNJ(X)\leq J(X)$ between the von Neumann--Jordan and James constants was established by Takahashi and Kato [J. Math. Anal. Appl. 359 (2009), 602--609], Wang [Proc. Amer. Math. Soc. 138 (2010), 695--701], and Yang and Li [Appl. Math. Lett. 23 (2010), 277--281], while related sharp estimates were obtained by Kato and Takahashi [Rend. Circ. Mat. Palermo (2) Suppl. 82 (2010), 75--91]. We sharpen this inequality to $\CNJ(X)\leq\JB(X)$, where $\JB(X)$ is the Birkhoff--James orthogonal James constant introduced by Baronti and Papini [Constr. Math. Anal. 5 (2022), 37--45]. Our proof employs optimal distance ellipses and alternating contact directions.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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