{"title":"Two subspace methods for frequency sparse graph signals","authors":"Tarek Emmrich, Martina Juhnke, Stefan Kunis","doi":"10.1016/j.acha.2024.101711","DOIUrl":"10.1016/j.acha.2024.101711","url":null,"abstract":"<div><div>We study signals that are sparse in graph spectral domain and develop explicit algorithms to reconstruct the support set as well as partial components from samples on few vertices of the graph. The number of required samples is independent of the total size of the graph and takes only local properties of the graph into account. Our results rely on an operator based framework for subspace methods and become effective when the spectral eigenfunctions are zero-free or linear independent on small sets of the vertices. The latter has recently been addressed using algebraic methods by the first author.</div></div>","PeriodicalId":55504,"journal":{"name":"Applied and Computational Harmonic Analysis","volume":"74 ","pages":"Article 101711"},"PeriodicalIF":2.6,"publicationDate":"2024-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142425139","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Approximation theory of wavelet frame based image restoration","authors":"Jian-Feng Cai , Jae Kyu Choi , Jianbin Yang","doi":"10.1016/j.acha.2024.101712","DOIUrl":"10.1016/j.acha.2024.101712","url":null,"abstract":"<div><div>In this paper, we analyze the error estimate of a wavelet frame based image restoration method from degraded and incomplete measurements. We present the error between the underlying original discrete image and the approximate solution which has the minimal <span><math><msub><mrow><mi>ℓ</mi></mrow><mrow><mn>1</mn></mrow></msub></math></span>-norm of the canonical wavelet frame coefficients among all possible solutions. Then we further connect the error estimate for the discrete model to the approximation to the underlying function from which the underlying image comes.</div></div>","PeriodicalId":55504,"journal":{"name":"Applied and Computational Harmonic Analysis","volume":"74 ","pages":"Article 101712"},"PeriodicalIF":2.6,"publicationDate":"2024-09-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142425140","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Donoho-Logan large sieve principles for the wavelet transform","authors":"Luís Daniel Abreu , Michael Speckbacher","doi":"10.1016/j.acha.2024.101709","DOIUrl":"10.1016/j.acha.2024.101709","url":null,"abstract":"<div><div>In this paper we formulate Donoho and Logan's large sieve principle for the wavelet transform on the Hardy space, adapting the concept of maximum Nyquist density to the hyperbolic geometry of the underlying space. The results provide deterministic guarantees for <span><math><msub><mrow><mi>L</mi></mrow><mrow><mn>1</mn></mrow></msub></math></span>-minimization methods and hold for a class of mother wavelets that constitutes an orthonormal basis of the Hardy space and can be associated with higher hyperbolic Landau levels. Explicit calculations of the basis functions reveal a connection with the Zernike polynomials. We prove a novel local reproducing formula for the spaces in consideration and use it to derive concentration estimates of the large sieve type for the corresponding wavelet transforms. We conclude with a discussion of optimality of localization and Lieb inequalities in the analytic case by building on recent results of Kulikov, Ramos and Tilli based on the groundbreaking methods of Nicola and Tilli. This leads to a sharp uncertainty principle and a local Lieb inequality for the wavelet transform.</div></div>","PeriodicalId":55504,"journal":{"name":"Applied and Computational Harmonic Analysis","volume":"74 ","pages":"Article 101709"},"PeriodicalIF":2.6,"publicationDate":"2024-09-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142425138","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Data-driven optimal shrinkage of singular values under high-dimensional noise with separable covariance structure with application","authors":"Pei-Chun Su , Hau-Tieng Wu","doi":"10.1016/j.acha.2024.101698","DOIUrl":"10.1016/j.acha.2024.101698","url":null,"abstract":"<div><p>We develop a data-driven optimal shrinkage algorithm, named <em>extended OptShrink</em> (eOptShrink), for matrix denoising with high-dimensional noise and a separable covariance structure. This noise is colored and dependent across samples. The algorithm leverages the asymptotic behavior of singular values and vectors of the noisy data's random matrix. Our theory includes the sticking property of non-outlier singular values, delocalization of weak signal singular vectors, and the spectral behavior of outlier singular values and vectors. We introduce three estimators: a novel rank estimator, an estimator for the spectral distribution of the pure noise matrix, and the optimal shrinker eOptShrink. Notably, eOptShrink does not require estimating the noise's separable covariance structure. We provide a theoretical guarantee for these estimators with a convergence rate. Through numerical simulations and comparisons with state-of-the-art optimal shrinkage algorithms, we demonstrate eOptShrink's application in extracting maternal and fetal electrocardiograms from single-channel trans-abdominal maternal electrocardiograms.</p></div>","PeriodicalId":55504,"journal":{"name":"Applied and Computational Harmonic Analysis","volume":"74 ","pages":"Article 101698"},"PeriodicalIF":2.6,"publicationDate":"2024-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142241768","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Construction of pairwise orthogonal Parseval frames generated by filters on LCA groups","authors":"Navneet Redhu , Anupam Gumber , Niraj K. Shukla","doi":"10.1016/j.acha.2024.101708","DOIUrl":"10.1016/j.acha.2024.101708","url":null,"abstract":"<div><p>The generalized translation invariant (GTI) systems unify the discrete frame theory of generalized shift-invariant systems with its continuous version, such as wavelets, shearlets, Gabor transforms, and others. This article provides sufficient conditions to construct pairwise orthogonal Parseval GTI frames in <span><math><msup><mrow><mi>L</mi></mrow><mrow><mn>2</mn></mrow></msup><mo>(</mo><mi>G</mi><mo>)</mo></math></span> satisfying the local integrability condition (LIC) and having the Calderón sum one, where <em>G</em> is a second countable locally compact abelian group. The pairwise orthogonality plays a crucial role in multiple access communications, hiding data, synthesizing superframes and frames, etc. Further, we provide a result for constructing <em>N</em> numbers of GTI Parseval frames, which are pairwise orthogonal. Consequently, we obtain an explicit construction of pairwise orthogonal Parseval frames in <span><math><msup><mrow><mi>L</mi></mrow><mrow><mn>2</mn></mrow></msup><mo>(</mo><mi>R</mi><mo>)</mo></math></span> and <span><math><msup><mrow><mi>L</mi></mrow><mrow><mn>2</mn></mrow></msup><mo>(</mo><mi>G</mi><mo>)</mo></math></span>, using B-splines as a generating function. In the end, the results are particularly discussed for wavelet systems.</p></div>","PeriodicalId":55504,"journal":{"name":"Applied and Computational Harmonic Analysis","volume":"74 ","pages":"Article 101708"},"PeriodicalIF":2.6,"publicationDate":"2024-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142172681","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Robust sparse recovery with sparse Bernoulli matrices via expanders","authors":"Pedro Abdalla","doi":"10.1016/j.acha.2024.101697","DOIUrl":"10.1016/j.acha.2024.101697","url":null,"abstract":"<div><p>Sparse binary matrices are of great interest in the field of sparse recovery, nonnegative compressed sensing, statistics in networks, and theoretical computer science. This class of matrices makes it possible to perform signal recovery with lower storage costs and faster decoding algorithms. In particular, Bernoulli (<em>p</em>) matrices formed by independent identically distributed (i.i.d.) Bernoulli (<em>p</em>) random variables are of practical relevance in the context of noise-blind recovery in nonnegative compressed sensing.</p><p>In this work, we investigate the robust nullspace property of Bernoulli (<em>p</em>) matrices. Previous results in the literature establish that such matrices can accurately recover <em>n</em>-dimensional <em>s</em>-sparse vectors with <span><math><mi>m</mi><mo>=</mo><mi>O</mi><mrow><mo>(</mo><mfrac><mrow><mi>s</mi></mrow><mrow><mi>c</mi><mo>(</mo><mi>p</mi><mo>)</mo></mrow></mfrac><mi>log</mi><mo></mo><mfrac><mrow><mi>e</mi><mi>n</mi></mrow><mrow><mi>s</mi></mrow></mfrac><mo>)</mo></mrow></math></span> measurements, where <span><math><mi>c</mi><mo>(</mo><mi>p</mi><mo>)</mo><mo>≤</mo><mi>p</mi></math></span> is a constant dependent only on the parameter <em>p</em>. These results suggest that in the sparse regime, as <em>p</em> approaches zero, the (sparse) Bernoulli (<em>p</em>) matrix requires significantly more measurements than the minimal necessary, as achieved by standard isotropic subgaussian designs. However, we show that this is not the case.</p><p>Our main result characterizes, for a wide range of sparsity levels <em>s</em>, the smallest <em>p</em> for which sparse recovery can be achieved with the minimal number of measurements. We also provide matching lower bounds to establish the optimality of our results and explore connections with the theory of invertibility of discrete random matrices and integer compressed sensing.</p></div>","PeriodicalId":55504,"journal":{"name":"Applied and Computational Harmonic Analysis","volume":"73 ","pages":"Article 101697"},"PeriodicalIF":2.6,"publicationDate":"2024-08-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S1063520324000745/pdfft?md5=da55acefd115269f8b0ce4f5a4a72295&pid=1-s2.0-S1063520324000745-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142083187","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"The G-invariant graph Laplacian part II: Diffusion maps","authors":"Eitan Rosen , Xiuyuan Cheng , Yoel Shkolnisky","doi":"10.1016/j.acha.2024.101695","DOIUrl":"10.1016/j.acha.2024.101695","url":null,"abstract":"<div><p>The diffusion maps embedding of data lying on a manifold has shown success in tasks such as dimensionality reduction, clustering, and data visualization. In this work, we consider embedding data sets that were sampled from a manifold which is closed under the action of a continuous matrix group. An example of such a data set is images whose planar rotations are arbitrary. The <em>G</em>-invariant graph Laplacian, introduced in Part I of this work, admits eigenfunctions in the form of tensor products between the elements of the irreducible unitary representations of the group and eigenvectors of certain matrices. We employ these eigenfunctions to derive diffusion maps that intrinsically account for the group action on the data. In particular, we construct both equivariant and invariant embeddings, which can be used to cluster and align the data points. We demonstrate the utility of our construction in the problem of random computerized tomography.</p></div>","PeriodicalId":55504,"journal":{"name":"Applied and Computational Harmonic Analysis","volume":"73 ","pages":"Article 101695"},"PeriodicalIF":2.6,"publicationDate":"2024-08-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141992698","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Afonso S. Bandeira , Dmitriy Kunisky , Dustin G. Mixon , Xinmeng Zeng
{"title":"On the concentration of Gaussian Cayley matrices","authors":"Afonso S. Bandeira , Dmitriy Kunisky , Dustin G. Mixon , Xinmeng Zeng","doi":"10.1016/j.acha.2024.101694","DOIUrl":"10.1016/j.acha.2024.101694","url":null,"abstract":"<div><p>Given a finite group, we study the Gaussian series of the matrices in the image of its left regular representation. We propose such random matrices as a benchmark for improvements to the noncommutative Khintchine inequality, and we highlight an application to the matrix Spencer conjecture.</p></div>","PeriodicalId":55504,"journal":{"name":"Applied and Computational Harmonic Analysis","volume":"73 ","pages":"Article 101694"},"PeriodicalIF":2.6,"publicationDate":"2024-08-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141910741","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Afonso S. Bandeira , Dustin G. Mixon , Stefan Steinerberger
{"title":"A lower bound for the Balan–Jiang matrix problem","authors":"Afonso S. Bandeira , Dustin G. Mixon , Stefan Steinerberger","doi":"10.1016/j.acha.2024.101696","DOIUrl":"10.1016/j.acha.2024.101696","url":null,"abstract":"<div><p>We prove the existence of a positive semidefinite matrix <span><math><mi>A</mi><mo>∈</mo><msup><mrow><mi>R</mi></mrow><mrow><mi>n</mi><mo>×</mo><mi>n</mi></mrow></msup></math></span> such that any decomposition into rank-1 matrices has to have factors with a large <span><math><msup><mrow><mi>ℓ</mi></mrow><mrow><mn>1</mn></mrow></msup><mo>−</mo></math></span>norm, more precisely<span><span><span><math><munder><mo>∑</mo><mrow><mi>k</mi></mrow></munder><msub><mrow><mi>x</mi></mrow><mrow><mi>k</mi></mrow></msub><msubsup><mrow><mi>x</mi></mrow><mrow><mi>k</mi></mrow><mrow><mo>⁎</mo></mrow></msubsup><mo>=</mo><mi>A</mi><mspace></mspace><mo>⇒</mo><mspace></mspace><munder><mo>∑</mo><mrow><mi>k</mi></mrow></munder><msubsup><mrow><mo>‖</mo><msub><mrow><mi>x</mi></mrow><mrow><mi>k</mi></mrow></msub><mo>‖</mo></mrow><mrow><mn>1</mn></mrow><mrow><mn>2</mn></mrow></msubsup><mo>≥</mo><mi>c</mi><msqrt><mrow><mi>n</mi></mrow></msqrt><msub><mrow><mo>‖</mo><mi>A</mi><mo>‖</mo></mrow><mrow><mn>1</mn></mrow></msub><mo>,</mo></math></span></span></span> where <em>c</em> is independent of <em>n</em>. This provides a lower bound for the Balan–Jiang matrix problem. The construction is probabilistic.</p></div>","PeriodicalId":55504,"journal":{"name":"Applied and Computational Harmonic Analysis","volume":"73 ","pages":"Article 101696"},"PeriodicalIF":2.6,"publicationDate":"2024-08-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141978297","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Johann S. Brauchart , Peter J. Grabner , Ian H. Sloan , Robert S. Womersley
{"title":"Needlets liberated","authors":"Johann S. Brauchart , Peter J. Grabner , Ian H. Sloan , Robert S. Womersley","doi":"10.1016/j.acha.2024.101693","DOIUrl":"10.1016/j.acha.2024.101693","url":null,"abstract":"<div><p>Spherical needlets were introduced by Narcowich, Petrushev, and Ward to provide a multiresolution sequence of polynomial approximations to functions on the sphere. The needlet construction makes use of integration rules that are exact for polynomials up to a given degree. The aim of the present paper is to relax the exactness of the integration rules by replacing them with QMC designs as introduced by Brauchart, Saff, Sloan, and Womersley (2014). Such integration rules (generalised here by allowing non-equal cubature weights) provide the same asymptotic order of convergence as exact rules for Sobolev spaces <span><math><msup><mrow><mi>H</mi></mrow><mrow><mi>s</mi></mrow></msup></math></span>, but are easier to obtain numerically. With such rules we construct “generalised needlets”. The paper provides an error analysis that allows the replacement of the original needlets by generalised needlets, and more generally, analyses a hybrid scheme in which the needlets for the lower levels are of the traditional kind, whereas the new generalised needlets are used for some number of higher levels. Numerical experiments complete the paper.</p></div>","PeriodicalId":55504,"journal":{"name":"Applied and Computational Harmonic Analysis","volume":"73 ","pages":"Article 101693"},"PeriodicalIF":2.6,"publicationDate":"2024-08-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S1063520324000708/pdfft?md5=9a180ff7ceb60a51f1d46ba86c076b69&pid=1-s2.0-S1063520324000708-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141910765","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}