Publications related to Convex optimization in sums of Banach spaces

WILD SOLUTIONS TO SCALAR EULER-LAGRANGE EQUATIONS

. We study very weak solutions to scalar Euler-Lagrange equations associated with quadratic convex functionals. We investigate whether W1,1 solutions are necessarily W 1,2 Nash and Schauder applicable. We answer this question positively for a suitable clas ...

Amer Mathematical Soc2024

Augmented Lagrangian Methods for Provable and Scalable Machine Learning

Mehmet Fatih Sahin

Non-convex constrained optimization problems have become a powerful framework for modeling a wide range of machine learning problems, with applications in k-means clustering, large- scale semidefinite programs (SDPs), and various other tasks. As the perfor ...

EPFL2023

Stability of Image-Reconstruction Algorithms

Michaël Unser, Sebastian Jonas Neumayer, Pol del Aguila Pla

Robustness and stability of image-reconstruction algorithms have recently come under scrutiny. Their importance to medical imaging cannot be overstated. We review the known results for the topical variational regularization strategies ( ℓ2 and ℓ1 regulariz ...

2023

Quadratic serendipity element shape functions on general planar polygons

Xiaodong Wei, Juan Cao

This paper proposes a method for the construction of quadratic serendipity element (QSE) shape functions on planar convex and concave polygons. Existing approaches for constructing QSE shape functions are linear combinations of the pair-wise products of ge ...

ELSEVIER SCIENCE SA2022

Variational Methods For Continuous-Domain Inverse Problems: the Quest for the Sparsest Solution

Thomas Jean Debarre

The goal of this thesis is to study continuous-domain inverse problems for the reconstruction of sparse signals and to develop efficient algorithms to solve such problems computationally. The task is to recover a signal of interest as a continuous function ...

EPFL2022

Proximal Point Imitation Learning

Volkan Cevher, Luca Viano, Igor Krawczuk, Angeliki Kamoutsi

This work develops new algorithms with rigorous efficiency guarantees for infinite horizon imitation learning (IL) with linear function approximation without restrictive coherence assumptions. We begin with the minimax formulation of the problem and then o ...

2022

Adaptive Stochastic Variance Reduction for Non-convex Finite-Sum Minimization

Volkan Cevher, Kimon Antonakopoulos, Efstratios Panteleimon Skoulakis, Leello Tadesse Dadi, Ali Kavis

We propose an adaptive variance-reduction method, called AdaSpider, for minimization of L-smooth, non-convex functions with a finite-sum structure. In essence, AdaSpider combines an AdaGrad-inspired [Duchi et al., 2011, McMahan & Streeter, 2010], but a fai ...

2022

Multikernel Regression with Sparsity Constraint

Michaël Unser, Shayan Aziznejad

In this paper, we provide a Banach-space formulation of supervised learning with generalized total-variation (gTV) regularization. We identify the class of kernel functions that are admissible in this framework. Then, we propose a variation of supervised l ...

2021

Continuous-Domain Formulation of Inverse Problems for Composite Sparse-Plus-Smooth Signals

Michaël Unser, Shayan Aziznejad, Thomas Jean Debarre

We present a novel framework for the reconstruction of 1D composite signals assumed to be a mixture of two additive components, one sparse and the other smooth, given a finite number of linear measurements. We formulate the reconstruction problem as a cont ...

IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC2021

Convergence of adaptive algorithms for constrained weakly convex optimization

Volkan Cevher, Ahmet Alacaoglu, Yurii Malitskyi

We analyze the adaptive first order algorithm AMSGrad, for solving a constrained stochastic optimization problem with a weakly convex objective. We prove the

\tilde O(t^{-1/2})

rate of convergence for the squared norm of the gradient of Moreau envelope, ...

2021

Convex optimization in sums of Banach spaces

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WILD SOLUTIONS TO SCALAR EULER-LAGRANGE EQUATIONS

Augmented Lagrangian Methods for Provable and Scalable Machine Learning

Stability of Image-Reconstruction Algorithms

Quadratic serendipity element shape functions on general planar polygons

Variational Methods For Continuous-Domain Inverse Problems: the Quest for the Sparsest Solution

Proximal Point Imitation Learning

Adaptive Stochastic Variance Reduction for Non-convex Finite-Sum Minimization

Multikernel Regression with Sparsity Constraint

Continuous-Domain Formulation of Inverse Problems for Composite Sparse-Plus-Smooth Signals

Convergence of adaptive algorithms for constrained weakly convex optimization

Augmented Lagrangian Methods for Provable and Scalable Machine Learning

Proximal Point Imitation Learning

Multikernel Regression with Sparsity Constraint

Continuous-Domain Formulation of Inverse Problems for Composite Sparse-Plus-Smooth Signals

WILD SOLUTIONS TO SCALAR EULER-LAGRANGE EQUATIONS

Quadratic serendipity element shape functions on general planar polygons

Stability of Image-Reconstruction Algorithms

Convergence of adaptive algorithms for constrained weakly convex optimization

Adaptive Stochastic Variance Reduction for Non-convex Finite-Sum Minimization

Variational Methods For Continuous-Domain Inverse Problems: the Quest for the Sparsest Solution