立方体上齐次多项式的几乎范数顶点
Almost norming vertices for homogeneous polynomials on the cube
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中文总结 AI 辅助
研究立方体上齐次多项式范数能否由顶点值近似恢复,证明在Bombieri高斯测度下相对损失以概率至多为n^{-1/2},顶点渐近构成范数集。
中文摘要 AI 辅助
设 $m\geq1$ 固定。我们考虑 $\nmathbb{R}^n$ 上实值 $m$ 次齐次多项式空间 $\nmathcal{P}_m(\nmathbb{R}^n)$,配备与 Bombieri 范数相关联的标准高斯测度 $\gamma_{m,n}$。我们研究典型多项式在 $\ell_\infty^n$ 单位球(即立方体 $[-1,1]^n$)上的范数如何从其顶点处的值恢复。对于 $P\in\nmathcal{P}_m(\nmathbb{R}^n)$,令 $M(P)=\max_{x\in[-1,1]^n}|P(x)|$,$V(P)=\max_{\varepsilon\in\{-1,1\}^n}|P(\varepsilon)|$。若 $P_n$ 按照 $\gamma_{m,n}$ 选取,我们证明相对损失 $1-\frac{V(P_n)}{M(P_n)}$ 在概率意义下阶数至多为 $n^{-1/2}$。因此,对于每个 $0<\beta<1/2$,当 $n\to\infty$ 时,$\gamma_{m,n}\left\{ P\in\nmathcal{P}_m(\nmathbb{R}^n): V(P)\geq (1-n^{-\beta})M(P) \right\}\longrightarrow1$。从而,关于 Bombieri 高斯测度,立方体的顶点对于固定次数的齐次多项式是渐近范数集。
英文摘要
Let $m\geq1$ be fixed. We consider the space $\mathcal{P}_m(\mathbb{R}^n)$ of real $m$-homogeneous polynomials on $\mathbb{R}^n$, endowed with the standard Gaussian measure $γ_{m,n}$ associated with the Bombieri norm. We study how well the norm of a typical polynomial on the unit ball of $\ell_\infty^n$, namely the cube $[-1,1]^n$, can be recovered from its values at the vertices. For $P\in\mathcal{P}_m(\mathbb{R}^n)$, set \[ M(P)=\max_{x\in[-1,1]^n}|P(x)|, \qquad V(P)=\max_{\varepsilon\in\{-1,1\}^n}|P(\varepsilon)|. \] If $P_n$ is chosen according to $γ_{m,n}$, we prove that the relative loss \[ 1-\frac{V(P_n)}{M(P_n)} \] is of order at most $n^{-1/2}$ in probability. Consequently, for every $0<β<1/2$, \[ γ_{m,n}\left\{ P\in\mathcal{P}_m(\mathbb{R}^n): V(P)\geq (1-n^{-β})M(P) \right\} \longrightarrow1 \] as $n\to\infty$. Thus, with respect to the Bombieri Gaussian measure, the vertices of the cube are asymptotically norming for homogeneous polynomials of fixed degree.
发表机构
- Universidad Torcuato Di Tella(托尔夸托·迪泰拉大学)
- CONICET(阿根廷国家科学研究委员会)
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