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An algorithmic framework, based on the difference of convex functions algorithm (DCA), is proposed for minimizing a class of concave sparse metrics for compressed sensing problems. The resulting algorithm iterates a sequence of $\ell_1$…

Information Theory · Computer Science 2016-11-02 Penghang Yin , Jack Xin

Sparse logistic regression is for classification and feature selection simultaneously. Although many studies have been done to solve $\ell_1$-regularized logistic regression, there is no equivalently abundant work on solving sparse logistic…

Machine Learning · Computer Science 2023-10-13 Mengyuan Zhang , Kai Liu

We introduce a framework based on bilevel programming that unifies gradient-based hyperparameter optimization and meta-learning. We show that an approximate version of the bilevel problem can be solved by taking into explicit account the…

Machine Learning · Statistics 2018-07-04 Luca Franceschi , Paolo Frasconi , Saverio Salzo , Riccardo Grazzi , Massimilano Pontil

In this paper we study the sparse coding problem in the context of sparse dictionary learning for image recovery. To this end, we consider and compare several state-of-the-art sparse optimization methods constructed using the shrinkage…

Computer Vision and Pattern Recognition · Computer Science 2025-04-03 Shima Shabani , Mohammadsadegh Khoshghiaferezaee , Michael Breuß

We propose an unrolled algorithm approach for learning spatially adaptive parameter maps in the framework of convolutional synthesis-based $\ell_1$ regularization. More precisely, we consider a family of pre-trained convolutional filters…

Machine Learning · Computer Science 2025-10-23 Andreas Kofler , Luca Calatroni , Christoph Kolbitsch , Kostas Papafitsoros

Modern statistical learning algorithms are capable of amazing flexibility, but struggle with interpretability. One possible solution is sparsity: making inference such that many of the parameters are estimated as being identically 0, which…

Methodology · Statistics 2023-05-15 Nathan Wycoff , Ali Arab , Katharine M. Donato , Lisa O. Singh

This paper considers solving the unconstrained $\ell_q$-norm ($0\leq q<1$) regularized least squares ($\ell_q$-LS) problem for recovering sparse signals in compressive sensing. We propose two highly efficient first-order algorithms via…

Information Theory · Computer Science 2016-03-16 Fei Wen , Yuan Yang , Peilin Liu , Rendong Ying , Yipeng Liu

Dictionary learning aims at seeking a dictionary under which the training data can be sparsely represented. Methods in the literature typically formulate the dictionary learning problem as an optimization w.r.t. two variables, i.e.,…

Signal Processing · Electrical Eng. & Systems 2021-10-27 Cheng Cheng , Wei Dai

In the synthesis model signals are represented as a sparse combinations of atoms from a dictionary. Dictionary learning describes the acquisition process of the underlying dictionary for a given set of training samples. While ideally this…

Machine Learning · Statistics 2015-03-11 Matthias Seibert , Martin Kleinsteuber , Rémi Gribonval , Rodolphe Jenatton , Francis Bach

Best subset selection is considered the `gold standard' for many sparse learning problems. A variety of optimization techniques have been proposed to attack this non-convex and NP-hard problem. In this paper, we investigate the dual forms…

Methodology · Statistics 2022-07-06 Shaogang Ren , Guanhua Fang , Ping Li

We propose a new approach to solving bilevel optimization problems, intermediate between solving full-system optimality conditions with a Newton-type approach, and treating the inner problem as an implicit function. The overall idea is to…

Optimization and Control · Mathematics 2024-05-08 Ensio Suonperä , Tuomo Valkonen

Compressed Sensing using $\ell_1$ regularization is among the most powerful and popular sparsification technique in many applications, but why has it not been used to obtain sparse deep learning model such as convolutional neural network…

Machine Learning · Computer Science 2021-10-06 Juncai He , Xiaodong Jia , Jinchao Xu , Lian Zhang , Liang Zhao

Information processing techniques based on sparseness have been actively studied in several disciplines. Among them, a mathematical framework to approximately express a given dataset by a combination of a small number of basis vectors of an…

Information Theory · Computer Science 2016-05-04 Tomoyuki Obuchi , Yoshiyuki Kabashima

The concept of sparsity has been extensively applied for regularization in image reconstruction. Typically, sparsifying transforms are either pre-trained on ground-truth images or adaptively trained during the reconstruction. Thereby,…

Image and Video Processing · Electrical Eng. & Systems 2022-03-07 Andreas Kofler , Christian Wald , Tobias Schaeffter , Markus Haltmeier , Christoph Kolbitsch

Learning dictionaries suitable for sparse coding instead of using engineered bases has proven effective in a variety of image processing tasks. This paper studies the optimization of dictionaries on image data where the representation is…

Machine Learning · Computer Science 2016-04-19 Markus Thom , Matthias Rapp , Günther Palm

Although disentangled representations are often said to be beneficial for downstream tasks, current empirical and theoretical understanding is limited. In this work, we provide evidence that disentangled representations coupled with sparse…

This paper investigates a general class of problems in which a lower bounded smooth convex function incorporating $\ell_{0}$ and $\ell_{2,0}$ regularization is minimized over a box constraint. Although such problems arise frequently in…

Optimization and Control · Mathematics 2025-11-26 Yuge Ye , Qingna Li

Over the past decade, learning a dictionary from input images for sparse modeling has been one of the topics which receive most research attention in image processing and compressed sensing. Most existing dictionary learning methods…

Image and Video Processing · Electrical Eng. & Systems 2021-04-27 Kai Liu , Yongjian Zhao , Hua Wang

$\ell_1$ based sparse regularization plays a central role in compressive sensing and image processing. In this paper, we propose $\ell_1$DecNet, as an unfolded network derived from a variational decomposition model incorporating $\ell_1$…

Image and Video Processing · Electrical Eng. & Systems 2025-07-01 Yumeng Ren , Yiming Gao , Chunlin Wu , Xue-cheng Tai

Models initialized from self-supervised pretraining may suffer from poor alignment with downstream tasks, reducing the extent to which subsequent fine-tuning can adapt pretrained features toward downstream objectives. To mitigate this, we…

Machine Learning · Computer Science 2026-02-11 Gustav Wagner Zakarias , Lars Kai Hansen , Zheng-Hua Tan