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This paper presents a hardness-aware deep metric learning (HDML) framework. Most previous deep metric learning methods employ the hard negative mining strategy to alleviate the lack of informative samples for training. However, this mining…

Computer Vision and Pattern Recognition · Computer Science 2019-12-05 Wenzhao Zheng , Zhaodong Chen , Jiwen Lu , Jie Zhou

For the first time, a globally convergent numerical method is developed and Lipschitz stability estimate is obtained for the challenging problem of travel time tomography in 3D for formally determined incomplete data. The semidiscrete case…

Numerical Analysis · Mathematics 2019-04-16 Michael V. Klibanov

In this paper a special piecewise linear system is studied. It is shown that, under a mild assumption, the semi-smooth Newton method applied to this system is well defined and the method generates a sequence that converges linearly to a…

Optimization and Control · Mathematics 2015-11-13 J. G. Barrios , J. Y. Bello Cruz , O. P. Ferreira , S. Z. Németh

The standard approach to compressive sampling considers recovering an unknown deterministic signal with certain known structure, and designing the sub-sampling pattern and recovery algorithm based on the known structure. This approach…

Information Theory · Computer Science 2016-02-03 Yen-Huan Li , Volkan Cevher

Semi-supervised learning has made significant strides in the medical domain since it alleviates the heavy burden of collecting abundant pixel-wise annotated data for semantic segmentation tasks. Existing semi-supervised approaches enhance…

Computer Vision and Pattern Recognition · Computer Science 2021-12-03 Xu Zheng , Chong Fu , Haoyu Xie , Jialei Chen , Xingwei Wang , Chiu-Wing Sham

Natural signals and images are well-known to be approximately sparse in transform domains such as Wavelets and DCT. This property has been heavily exploited in various applications in image processing and medical imaging. Compressed sensing…

Machine Learning · Computer Science 2015-10-26 Saiprasad Ravishankar , Yoram Bresler

We study the problem of minimizing a $m$-weakly convex and possibly nonsmooth function. Weak convexity provides a broad framework that subsumes convex, smooth, and many composite nonconvex functions. In this work, we propose a…

Optimization and Control · Mathematics 2025-09-04 Feng-Yi Liao , Yang Zheng

We study the problem of sampling from a distribution $p^*(x) \propto \exp\left(-U(x)\right)$, where the function $U$ is $L$-smooth everywhere and $m$-strongly convex outside a ball of radius $R$, but potentially nonconvex inside this ball.…

We propose a globally convergent numerical method to compute solutions to a general class of quasi-linear PDEs with both Neumann and Dirichlet boundary conditions. Combining the quasi-reversibility method and a suitable Carleman weight…

Numerical Analysis · Mathematics 2022-10-10 Loc Hoang Nguyen

Subgradient methods converge linearly on a convex function that grows sharply away from its solution set. In this work, we show that the same is true for sharp functions that are only weakly convex, provided that the subgradient methods are…

Optimization and Control · Mathematics 2018-03-08 Damek Davis , Dmitriy Drusvyatskiy , Kellie J. MacPhee , Courtney Paquette

Implicit sampling is a weighted sampling method that is used in data assimilation, where one sequentially updates estimates of the state of a stochastic model based on a stream of noisy or incomplete data. Here we describe how to use…

Numerical Analysis · Mathematics 2016-01-20 Matthias Morzfeld , Xuemin Tu , Jon Wilkening , Alexandre J. Chorin

Deep regression is an important problem with numerous applications. These range from computer vision tasks such as age estimation from photographs, to medical tasks such as ejection fraction estimation from echocardiograms for disease…

Computer Vision and Pattern Recognition · Computer Science 2023-02-16 Weihang Dai , Xiaomeng Li , Kwang-Ting Cheng

Electrical Impedance Tomography (EIT) is a powerful tool for non-destructive evaluation, state estimation, and process tomography - among numerous other use cases. For these applications, and in order to reliably reconstruct images of a…

Signal Processing · Electrical Eng. & Systems 2020-01-31 Danny Smyl , Dong Liu

We consider linear prediction with a convex Lipschitz loss, or more generally, stochastic convex optimization problems of generalized linear form, i.e.~where each instantaneous loss is a scalar convex function of a linear function. We show…

Machine Learning · Computer Science 2022-11-01 Idan Amir , Roi Livni , Nathan Srebro

We present a novel deep learning approach to approximate the solution of large, sparse, symmetric, positive-definite linear systems of equations. These systems arise from many problems in applied science, e.g., in numerical methods for…

Machine Learning · Computer Science 2022-10-04 Ayano Kaneda , Osman Akar , Jingyu Chen , Victoria Kala , David Hyde , Joseph Teran

In this work, we consider convex optimization problems with smooth objective function and nonsmooth functional constraints. We propose a new stochastic gradient algorithm, called Stochastic Halfspace Approximation Method (SHAM), to solve…

Optimization and Control · Mathematics 2024-12-04 Nitesh Kumar Singh , Ion Necoara

A graph-based classification method is proposed for semi-supervised learning in the case of Euclidean data and for classification in the case of graph data. Our manifold learning technique is based on a convex optimization problem involving…

Machine Learning · Computer Science 2019-01-29 Carlos M. Alaíz , Michaël Fanuel , Johan A. K. Suykens

Compressive sampling is a new paradigm for sampling, based on sparseness of signals or signal representations. It is much less restrictive than Nyquist-Shannon sampling theory and thus explains and systematises the widespread experience…

Instrumentation and Methods for Astrophysics · Physics 2015-05-28 Feng Li , Tim J. Cornwell , Frank de Hoog

We propose a sparse regression method based on the non-concave penalized density power divergence loss function which is robust against infinitesimal contamination in very high dimensionality. Present methods of sparse and robust regression…

Methodology · Statistics 2021-05-18 Abhik Ghosh , Subhabrata Majumdar

Accurate signal recovery or image reconstruction from indirect and possibly undersampled data is a topic of considerable interest; for example, the literature in the recent field of compressed sensing is already quite immense. Inspired by…

Optimization and Control · Mathematics 2011-04-15 Stephen Becker , Jerome Bobin , Emmanuel Candes