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Manifold learning in metric spaces 度量空间中的流形学习
IF 3.2 2区 数学 Q1 MATHEMATICS, APPLIED Pub Date : 2025-09-14 DOI: 10.1016/j.acha.2025.101813
Liane Xu , Amit Singer
Laplacian-based methods are popular for the dimensionality reduction of data lying in RN. Several theoretical results for these algorithms depend on the fact that the Euclidean distance locally approximates the geodesic distance on the underlying submanifold which the data are assumed to lie on. However, for some applications, other metrics, such as the Wasserstein distance, may provide a more appropriate notion of distance than the Euclidean distance. We provide a framework that generalizes the problem of manifold learning to metric spaces and study when a metric satisfies sufficient conditions for the pointwise convergence of the graph Laplacian.
基于拉普拉斯的降维方法是对RN中的数据进行降维的常用方法。这些算法的几个理论结果依赖于这样一个事实,即欧几里得距离局部近似于假定数据所在的底层子流形上的测地线距离。然而,对于某些应用,其他度量,如沃瑟斯坦距离,可能提供比欧几里得距离更合适的距离概念。我们提供了一个将流形学习问题推广到度量空间的框架,并研究了一个度量何时满足图拉普拉斯算子的点向收敛的充分条件。
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引用次数: 0
Gaussian random fields and monogenic images 高斯随机场和单基因图像
IF 3.2 2区 数学 Q1 MATHEMATICS, APPLIED Pub Date : 2025-09-14 DOI: 10.1016/j.acha.2025.101814
Hermine Biermé , Philippe Carré , Céline Lacaux , Claire Launay
In this paper, we focus on lighthouse anisotropic fractional Brownian fields (AFBFs), whose self-similarity depends solely on the so-called Hurst parameter, while anisotropy is revealed through the opening angle of an oriented spectral cone. This fractional field generalizes fractional Brownian motion and models rough natural phenomena. Consequently, estimating the model parameters is a crucial issue for modeling and analyzing real data. This work introduces the representation of AFBFs using the monogenic transform. Combined with a multiscale analysis, the monogenic signal is built from the Riesz transform to extract local orientation and structural information from an image at different scales. We then exploit the monogenic signal to define new estimators of AFBF parameters in the particular case of lighthouse fields. We prove that the estimators of anisotropy and self-similarity index (called the Hurst index) are strongly consistent. We demonstrate that these estimators verify asymptotic normality with explicit variance. We also introduce an estimator of the texture orientation. We propose a numerical scheme for calculating the monogenic representation and strategies for computing the estimators. Numerical results illustrate the performance of these estimators. Regarding Hurst index estimation, estimators based on the monogenic representation of random fields appear to be more robust than those using only the Riesz transform. We show that both estimation methods outperform standard estimation procedures in the isotropic case and provide excellent results for all degrees of anisotropy.
本文主要研究灯塔各向异性分数布朗场(AFBFs),其自相似性仅取决于所谓的Hurst参数,而各向异性是通过定向光谱锥的开口角度来揭示的。这个分数场推广了分数布朗运动,并模拟了粗糙的自然现象。因此,模型参数的估计是实际数据建模和分析的关键问题。这项工作介绍了使用单基因变换的afbf的表示。结合多尺度分析,利用Riesz变换构建单基因信号,提取不同尺度图像的局部方向和结构信息。然后我们利用单基因信号在灯塔场的特殊情况下定义AFBF参数的新估计器。我们证明了各向异性估计量和自相似指数(称为Hurst指数)是强一致的。我们证明了这些估计验证了具有显式方差的渐近正态性。我们还引入了纹理方向的估计器。我们提出了一种计算单基因表示的数值格式和计算估计量的策略。数值结果说明了这些估计器的性能。对于Hurst指数估计,基于随机场单基因表示的估计器似乎比仅使用Riesz变换的估计器更稳健。研究表明,这两种估计方法在各向同性情况下都优于标准估计程序,并为所有各向异性程度提供了出色的结果。
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引用次数: 0
Demystifying Carleson frames 揭开卡尔森镜框的神秘面纱
IF 3.2 2区 数学 Q1 MATHEMATICS, APPLIED Pub Date : 2025-09-12 DOI: 10.1016/j.acha.2025.101811
Ilya Krishtal, Brendan Miller
We study spanning properties of Carleson systems and prove a recent conjecture on frame subsequences of Carleson frames. In particular, we show that if {Tkφ}k=0 is a Carleson frame, then every subsequence of the form {TNk+jkφ}k=0 where NN and 0jk<N is also a frame.
我们研究了Carleson系统的生成性质,并证明了Carleson框架子序列的一个新猜想。特别地,我们证明了如果{Tkφ}k=0∞是一个Carleson帧,那么形式为{TNk+jkφ}k=0∞且N∈N且0≤jk<;N的每个子序列也是一个帧。
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引用次数: 0
Pattern recovery by SLOPE 利用斜率恢复模式
IF 3.2 2区 数学 Q1 MATHEMATICS, APPLIED Pub Date : 2025-09-08 DOI: 10.1016/j.acha.2025.101810
Małgorzata Bogdan , Xavier Dupuis , Piotr Graczyk , Bartosz Kołodziejek , Tomasz Skalski , Patrick Tardivel , Maciej Wilczyński
SLOPE is a popular method for dimensionality reduction in high-dimensional regression. Its estimated coefficients can be zero, yielding sparsity, or equal in absolute value, yielding clustering. As a result, SLOPE can eliminate irrelevant predictors and identify groups of predictors that have the same influence on the response. The concept of the SLOPE pattern allows us to formalize and study its sparsity and clustering properties. In particular, the SLOPE pattern of a coefficient vector captures the signs of its components (positive, negative, or zero), the clusters (groups of coefficients with the same absolute value), and the ranking of those clusters. This is the first paper to thoroughly investigate the consistency of the SLOPE pattern. We establish necessary and sufficient conditions for SLOPE pattern recovery, which in turn enable the derivation of an irrepresentability condition for SLOPE given a fixed design matrix X. These results lay the groundwork for a comprehensive asymptotic analysis of SLOPE pattern consistency.
SLOPE是高维回归中常用的降维方法。其估计系数可以为零,产生稀疏性,或者绝对值相等,产生聚类。因此,SLOPE可以消除不相关的预测因子,并确定对响应具有相同影响的预测因子组。SLOPE模式的概念允许我们形式化并研究其稀疏性和聚类属性。特别是,系数向量的SLOPE模式捕获其分量的符号(正、负或零)、聚类(具有相同绝对值的系数组)以及这些聚类的排名。这是第一篇深入研究SLOPE模式一致性的论文。我们建立了SLOPE图恢复的充分必要条件,从而推导出给定固定设计矩阵x的SLOPE的不可表示性条件,这些结果为斜率图一致性的全面渐近分析奠定了基础。
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引用次数: 0
Optimal lower Lipschitz bounds for ReLU layers, saturation, and phase retrieval 最优下Lipschitz边界的ReLU层,饱和度和相位检索
IF 3.2 2区 数学 Q1 MATHEMATICS, APPLIED Pub Date : 2025-08-28 DOI: 10.1016/j.acha.2025.101801
Daniel Freeman , Daniel Haider
The injectivity of ReLU layers in neural networks, the recovery of vectors from clipped or saturated measurements, and (real) phase retrieval in Rn allow for a similar problem formulation and characterization using frame theory. In this paper, we revisit all three problems with a unified perspective and derive lower Lipschitz bounds for ReLU layers and clipping which are analogous to the previously known result for phase retrieval and are optimal up to a constant factor.
神经网络中ReLU层的注入性,从裁剪或饱和测量中恢复向量,以及Rn中的(真实)相位检索允许使用框架理论进行类似的问题表述和表征。在本文中,我们以统一的视角重新审视了这三个问题,并推导了ReLU层和裁剪的下Lipschitz界,这类似于先前已知的相位检索结果,并且在常量因子下是最优的。
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引用次数: 0
Sparse free deconvolution under unknown noise level via eigenmatrix 基于特征矩阵的未知噪声下的稀疏自由反卷积
IF 3.2 2区 数学 Q1 MATHEMATICS, APPLIED Pub Date : 2025-08-14 DOI: 10.1016/j.acha.2025.101802
Lexing Ying
This note considers the spectral estimation problems of sparse spectral measures under unknown noise levels. The main technical tool is the eigenmatrix method for solving unstructured sparse recovery problems. When the noise level is determined, the free deconvolution reduces the problem to an unstructured sparse recovery problem to which the eigenmatrix method can be applied. To determine the unknown noise level, we propose an optimization problem based on the singular values of an intermediate matrix of the eigenmatrix method. Numerical results are provided for both the additive and multiplicative free deconvolutions.
本文研究未知噪声水平下稀疏谱测度的谱估计问题。求解非结构化稀疏恢复问题的主要技术工具是特征矩阵法。当噪声水平确定后,自由反褶积将问题简化为可应用特征矩阵方法的非结构化稀疏恢复问题。为了确定未知噪声水平,我们提出了一个基于特征矩阵法中间矩阵奇异值的优化问题。给出了加性和乘性自由反卷积的数值结果。
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引用次数: 0
Sharp error estimates for target measure diffusion maps with applications to the committor problem 针对提交者问题的应用程序的目标度量扩散映射的精确误差估计
IF 3.2 2区 数学 Q1 MATHEMATICS, APPLIED Pub Date : 2025-08-14 DOI: 10.1016/j.acha.2025.101803
Shashank Sule , Luke Evans , Maria Cameron
We obtain asymptotically sharp error estimates for the consistency error of the Target Measure Diffusion map (TMDmap) (Banisch et al. 2020), a variant of diffusion maps featuring importance sampling and hence allowing input data drawn from an arbitrary density. The derived error estimates include the bias error and the variance error. The resulting convergence rates are consistent with the approximation theory of graph Laplacians. The key novelty of our results lies in the explicit quantification of all the prefactors on leading-order terms. We also prove an error estimate for solutions of Dirichlet BVPs obtained using TMDmap, showing that the solution error is controlled by consistency error. We use these results to study an important application of TMDmap in the analysis of rare events in systems governed by overdamped Langevin dynamics using the framework of transition path theory (TPT). The cornerstone ingredient of TPT is the solution of the committor problem, a boundary value problem for the backward Kolmogorov PDE. Remarkably, we find that the TMDmap algorithm is particularly suited as a meshless solver to the committor problem due to the cancellation of several error terms in the prefactor formula. Furthermore, significant improvements in bias and variance errors occur when using a quasi-uniform sampling density. Our numerical experiments show that these improvements in accuracy are realizable in practice when using δ-nets as spatially uniform inputs to the TMDmap algorithm.
我们获得了目标测量扩散图(TMDmap)一致性误差的渐近尖锐误差估计(Banisch et al. 2020),这是扩散图的一种变体,具有重要采样功能,因此允许从任意密度提取输入数据。得到的误差估计包括偏置误差和方差误差。所得的收敛速率符合图拉普拉斯算子的近似理论。我们的结果的关键新颖之处在于对所有导序项上的前因子的显式量化。我们还证明了用TMDmap得到的Dirichlet bvp解的误差估计,表明解的误差是由一致性误差控制的。我们利用这些结果研究了TMDmap在利用过渡路径理论(TPT)框架分析由过阻尼朗格万动力学控制的系统中的罕见事件中的重要应用。TPT的基石是解决提交者问题,即后向Kolmogorov PDE的边值问题。值得注意的是,我们发现TMDmap算法特别适合作为提交问题的无网格求解器,因为它取消了前因子公式中的几个误差项。此外,当使用准均匀采样密度时,偏差和方差误差会得到显著改善。我们的数值实验表明,当使用δ-nets作为空间均匀输入到TMDmap算法时,这些精度的提高在实践中是可以实现的。
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引用次数: 0
Large data limit of the MBO scheme for data clustering: Γ-convergence of the thresholding energies 数据聚类MBO方案的大数据限制:阈值能量Γ-convergence
IF 3.2 2区 数学 Q1 MATHEMATICS, APPLIED Pub Date : 2025-08-14 DOI: 10.1016/j.acha.2025.101800
Tim Laux , Jona Lelmi
In this work we present the first rigorous analysis of the MBO scheme for data clustering in the large data limit. Each iteration of the scheme corresponds to one step of implicit gradient descent for the thresholding energy on the similarity graph of some dataset. For a subset of the nodes of the graph, the thresholding energy at time h measures the amount of heat transferred from the subset to its complement at time h, rescaled by a factor h. It is then natural to think that outcomes of the MBO scheme are (local) minimizers of this energy. We prove that the algorithm is consistent, in the sense that these (local) minimizers converge to (local) minimizers of a suitably weighted optimal partition problem.
在这项工作中,我们首次提出了在大数据限制下数据聚类的MBO方案的严格分析。该方案的每一次迭代对应于某一数据集的相似图阈值能量隐式梯度下降的一步。对于图中节点的一个子集,h时刻的阈值能量测量了从该子集到h时刻的补体传递的热量,通过因子h重新缩放。然后很自然地认为MBO方案的结果是该能量的(局部)最小值。我们证明了该算法是一致的,即这些(局部)极小值收敛于一个适当加权最优划分问题的(局部)极小值。
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引用次数: 0
The Wigner distribution of Gaussian tempered generalized stochastic processes 高斯缓和广义随机过程的Wigner分布
IF 3.2 2区 数学 Q1 MATHEMATICS, APPLIED Pub Date : 2025-08-13 DOI: 10.1016/j.acha.2025.101799
Patrik Wahlberg
We define the Wigner distribution of a tempered generalized stochastic process that is complex-valued symmetric Gaussian. This gives a time-frequency generalized stochastic process defined on the phase space. We study its covariance and our main result is a formula for the Weyl symbol of the covariance operator, expressed in terms of the Weyl symbol of the covariance operator of the original generalized stochastic process.
我们定义了复值对称高斯的调和广义随机过程的Wigner分布。给出了一个定义在相空间上的时频广义随机过程。我们研究了它的协方差,我们的主要结果是一个协方差算子的Weyl符号的公式,用原始广义随机过程的协方差算子的Weyl符号表示。
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引用次数: 0
Permutation-invariant representations with applications to graph deep learning 排列不变表示及其在图深度学习中的应用
IF 3.2 2区 数学 Q1 MATHEMATICS, APPLIED Pub Date : 2025-08-06 DOI: 10.1016/j.acha.2025.101798
Radu Balan , Naveed Haghani , Maneesh Singh
This paper presents primarily two Euclidean embeddings of the quotient space generated by matrices that are identified modulo arbitrary row permutations. The original application is in deep learning on graphs where the learning task is invariant to node relabeling. Two embedding schemes are introduced, one based on sorting and the other based on algebras of multivariate polynomials. While both embeddings exhibit a computational complexity exponential in problem size, the sorting based embedding is globally bi-Lipschitz and admits a low dimensional target space. Additionally, an almost everywhere injective scheme can be implemented with minimal redundancy and low computational cost. In turn, this proves that almost any classifier can be implemented with an arbitrary small loss of performance. Numerical experiments are carried out on two datasets, a chemical compound dataset (QM9) and a proteins dataset (PROTEINS_FULL).
本文主要给出了由模任意行置换识别的矩阵所产生的商空间的两种欧几里得嵌入。最初的应用是在图上的深度学习,其中学习任务对节点重新标记是不变的。介绍了两种嵌入方案,一种基于排序,另一种基于多元多项式代数。虽然这两种嵌入方法在问题规模上都表现出指数级的计算复杂度,但基于排序的嵌入方法是全局双lipschitz的,并且允许低维目标空间。此外,几乎处处注入方案可以实现最小的冗余和较低的计算成本。反过来,这证明了几乎任何分类器都可以以任意小的性能损失来实现。在化学化合物数据集(QM9)和蛋白质数据集(PROTEINS_FULL)上进行了数值实验。
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引用次数: 0
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Applied and Computational Harmonic Analysis
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