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1703.07809 2026-05-10 math.NA cs.NA math.ST stat.TH

Empirical Risk Minimization as Parameter Choice Rule for General Linear Regularization Methods

经验风险最小化作为通用线性正则化方法的参数选择规则

Housen Li, Frank Werner

AI总结 本文研究了通过经验风险最小化选择正则化参数在统计反问题中的应用,证明了该方法在一般设定下的最优性,并通过数值模拟验证了其在有限样本中的有效性。

Journal ref Ann. Inst. H. Poincaré Probab. Statist. 56(1): 405-427 (February 2020)

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AI中文摘要

我们考虑了从含噪测量 $Y = Tf + σξ$ 恢复 $f$ 的统计反问题,其中 $ξ$ 是高斯白噪声,$T$ 是在Hilbert空间之间的紧算子。考虑一般重建方法 $\hat f_α= q_α\left(T^*T\right)T^*Y$,其中 $q_α$ 是有序滤波器,我们通过最小化预测风险的无偏估计来选择正则化参数 $α$。对应的参数 $α_{\mathrm{pred}}$ 及其使用在文献中已知,但在此一般设定中,oracle不等式和最优性结果尚不清楚。我们证明了一个(广义)oracle不等式,将直接风险 $\mathbb E\left[\Vert f - \hat f_{α_{\mathrm{pred}}}\Vert^2\right]$ 与oracle预测风险 $\inf_{α>0}\mathbb E\left[\Vert Tf - T\hat f_α\Vert^2\right]$ 关联。从该oracle不等式,我们得出所研究的参数选择规则具有最优顺序。最后,我们还展示了数值模拟,支持该方法的最优顺序性和有限样本中的参数选择质量。

英文摘要

We consider the statistical inverse problem to recover $f$ from noisy measurements $Y = Tf + σξ$ where $ξ$ is Gaussian white noise and $T$ a compact operator between Hilbert spaces. Considering general reconstruction methods of the form $\hat f_α= q_α\left(T^*T\right)T^*Y$ with an ordered filter $q_α$, we investigate the choice of the regularization parameter $α$ by minimizing an unbiased estimate of the predictive risk $\mathbb E\left[\Vert Tf - T\hat f_α\Vert^2\right]$. The corresponding parameter $α_{\mathrm{pred}}$ and its usage are well-known in the literature, but oracle inequalities and optimality results in this general setting are unknown. We prove a (generalized) oracle inequality, which relates the direct risk $\mathbb E\left[\Vert f - \hat f_{α_{\mathrm{pred}}}\Vert^2\right]$ with the oracle prediction risk $\inf_{α>0}\mathbb E\left[\Vert Tf - T\hat f_α\Vert^2\right]$. From this oracle inequality we are then able to conclude that the investigated parameter choice rule is of optimal order. Finally we also present numerical simulations, which support the order optimality of the method and the quality of the parameter choice in finite sample situations.