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In this paper we analyze several inexact fast augmented Lagrangian methods for solving linearly constrained convex optimization problems. Mainly, our methods rely on the combination of excessive-gap-like smoothing technique developed in…

Optimization and Control · Mathematics 2015-05-14 Andrei Patrascu , Ion Necoara , Quoc Tran-Dinh

Diverse inverse problems in imaging can be cast as variational problems composed of a task-specific data fidelity term and a regularization term. In this paper, we propose a novel learnable general-purpose regularizer exploiting recent…

Optimization and Control · Mathematics 2020-02-19 Erich Kobler , Alexander Effland , Karl Kunisch , Thomas Pock

Computing an optimal classification tree that provably maximizes training performance within a given size limit, is NP-hard, and in practice, most state-of-the-art methods do not scale beyond computing optimal trees of depth three.…

Machine Learning · Computer Science 2025-01-15 Catalin E. Brita , Jacobus G. M. van der Linden , Emir Demirović

Image segmentation is an important task in the domain of computer vision and medical imaging. In natural and medical images, intensity inhomogeneity, i.e. the varying image intensity, occurs often and it poses considerable challenges for…

Image and Video Processing · Electrical Eng. & Systems 2019-04-04 Raymond Chan , Hongfei Yang , Tieyong Zeng

Numerous tasks in imaging and vision can be formulated as variational problems over vector-valued maps. We approach the relaxation and convexification of such vectorial variational problems via a lifting to the space of currents. To that…

Computer Vision and Pattern Recognition · Computer Science 2019-05-03 Thomas Möllenhoff , Daniel Cremers

This study presents the development of a spatially adaptive weighting strategy for Total Variation regularization, aimed at addressing under-determined linear inverse problems. The method leverages the rapid computation of an accurate…

Numerical Analysis · Mathematics 2025-01-20 Elena Morotti , Davide Evangelista , Andrea Sebastiani , Elena Loli Piccolomini

Magnetic resonance imaging (MRI) is a versatile imaging technique that allows different contrasts depending on the acquisition parameters. Many clinical imaging studies acquire MRI data for more than one of these contrasts---such as for…

Numerical Analysis · Mathematics 2017-10-06 Matthias J. Ehrhardt , Marta M. Betcke

The puzzle of computer vision might find new challenging solutions when we realize that most successful methods are working at image level, which is remarkably more difficult than processing directly visual streams, just as happens in…

Computer Vision and Pattern Recognition · Computer Science 2018-07-18 Alessandro Betti , Marco Gori , Stefano Melacci

We consider total variation minimization for manifold valued data. We propose a cyclic proximal point algorithm and a parallel proximal point algorithm to minimize TV functionals with $\ell^p$-type data terms in the manifold case. These…

Optimization and Control · Mathematics 2014-12-12 Andreas Weinmann , Laurent Demaret , Martin Storath

The paper surveys variational approaches for image reconstruction in dynamic inverse problems. Emphasis is on methods that rely on parametrised temporal models. These are here encoded as diffeomorphic deformations with time dependent…

Image and Video Processing · Electrical Eng. & Systems 2020-07-21 Andreas Hauptmann , Ozan Öktem , Carola Schönlieb

Several algorithms build on the perfect phylogeny model to infer evolutionary trees. This problem is particularly hard when evolutionary trees are inferred from the fraction of genomes that have mutations in different positions, across…

Data Structures and Algorithms · Computer Science 2018-12-31 Bei Jia , Surjyendu Ray , Sam Safavi , José Bento

In this work we consider algorithms for reconstructing time-varying data into a finite sum of discrete trajectories, alternatively, an off-the-grid sparse-spikes decomposition which is continuous in time. Recent work showed that this…

Optimization and Control · Mathematics 2022-12-26 Vincent Duval , Robert Tovey

This paper investigates convex quadratic optimization problems involving $n$ indicator variables, each associated with a continuous variable, particularly focusing on scenarios where the matrix $Q$ defining the quadratic term is positive…

Optimization and Control · Mathematics 2024-04-15 Aaresh Bhathena , Salar Fattahi , Andrés Gómez , Simge Küçükyavuz

We consider drawings of trees in which all edges incident to leaves can be extended to infinite rays without crossing, partitioning the plane into infinite convex polygons. Among all such drawings we seek the one maximizing the angular…

Computational Geometry · Computer Science 2007-05-23 Josiah Carlson , David Eppstein

We present a convex approach to probabilistic segmentation and modeling of time series data. Our approach builds upon recent advances in multivariate total variation regularization, and seeks to learn a separate set of parameters for the…

Machine Learning · Statistics 2015-11-17 Matt Wytock , J. Zico Kolter

Using deep neural networks to predict the solutions of AC optimal power flow (ACOPF) problems has been an active direction of research. However, because the ACOPF is nonconvex, it is difficult to construct a good data set that contains…

Systems and Control · Electrical Eng. & Systems 2021-10-06 Ling Zhang , Baosen Zhang

Dynamic programming on tree decompositions is a frequently used approach to solve otherwise intractable problems on instances of small treewidth. In recent work by Bodlaender et al., it was shown that for many connectivity problems, there…

Data Structures and Algorithms · Computer Science 2013-06-03 Stefan Fafianie , Hans L. Bodlaender , Jesper Nederlof

We consider the problem of minimizing the sum of submodular set functions assuming minimization oracles of each summand function. Most existing approaches reformulate the problem as the convex minimization of the sum of the corresponding…

Machine Learning · Computer Science 2019-05-28 K S Sesh Kumar , Francis Bach , Thomas Pock

We introduce discretizations of infinite-dimensional optimization problems with total variation regularization and integrality constraints on the optimization variables. We advance the discretization of the dual formulation of the total…

Numerical Analysis · Mathematics 2024-11-18 Annika Schiemann , Paul Manns

Continual learning is inherently a constrained learning problem. The goal is to learn a predictor under a no-forgetting requirement. Although several prior studies formulate it as such, they do not solve the constrained problem explicitly.…

Machine Learning · Computer Science 2024-06-03 Juan Elenter , Navid NaderiAlizadeh , Tara Javidi , Alejandro Ribeiro