arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 2401.16612stat.MLcs.LG
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用于逆问题稀疏正则化的高斯混合学习

Learning a Gaussian Mixture for Sparsity Regularization in Inverse Problems

MaLGa Center, Department of Mathematics, University of Genoa(马尔加中心,数学系,热那亚大学);Department of Mathematics, University of Bologna(数学系,博洛尼亚大学)

Giovanni S. Alberti, Luca Ratti, Matteo Santacesaria, Silvia Sciutto

AI总结:

该研究提出基于退化高斯混合的概率稀疏先验,构建可解释为线性逆问题贝叶斯估计器的神经网络及监督/无监督训练策略,在一维数据集上的重建均方误差优于多种经典稀疏正则化方法。

摘要:

在逆问题中,人们普遍认为引入稀疏先验会对解产生正则化效果。该方法基于先验假设:未知量可在某个基下用有限个显著分量恰当表示,而大多数系数接近零。这种情况在现实场景中很常见,例如分段平滑信号就符合该特性。本研究提出一种概率稀疏先验,其形式为退化高斯混合模型,能够针对通用基建模稀疏性。在此前提下,我们设计了一个可被解释为线性逆问题贝叶斯估计器的神经网络。此外,我们还提出了有监督和无监督两种训练策略来估计该网络的参数。为评估方法的有效性,我们与常用的稀疏促进正则化技术(即LASSO、组LASSO、迭代硬阈值、稀疏编码/字典学习)进行了数值对比。值得注意的是,在所有用于对比的一维数据集上,我们的重建结果均始终表现出更低的均方误差值,即便在数据集显著偏离高斯混合模型的情况下也是如此。

英文摘要:

In inverse problems, it is widely recognized that the incorporation of a sparsity prior yields a regularization effect on the solution. This approach is grounded on the a priori assumption that the unknown can be appropriately represented in a basis with a limited number of significant components, while most coefficients are close to zero. This occurrence is frequently observed in real-world scenarios, such as with piecewise smooth signals. In this study, we propose a probabilistic sparsity prior formulated as a mixture of degenerate Gaussians, capable of modeling sparsity with respect to a generic basis. Under this premise, we design a neural network that can be interpreted as the Bayes estimator for linear inverse problems. Additionally, we put forth both a supervised and an unsupervised training strategy to estimate the parameters of this network. To evaluate the effectiveness of our approach, we conduct a numerical comparison with commonly employed sparsity-promoting regularization techniques, namely LASSO, group LASSO, iterative hard thresholding, and sparse coding/dictionary learning. Notably, our reconstructions consistently exhibit lower mean square error values across all $1$D datasets utilized for the comparisons, even in cases where the datasets significantly deviate from a Gaussian mixture model.

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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