Search Results for author: Panagiotis Patrinos

Found 33 papers, 18 papers with code

Forward-backward envelope for the sum of two nonconvex functions: Further properties and nonmonotone line-search algorithms

5 code implementations20 Jun 2016 Andreas Themelis, Lorenzo Stella, Panagiotis Patrinos

Extending previous results we show that, despite being nonsmooth for fully nonconvex problems, the FBE still enjoys favorable first- and second-order properties which are key for the convergence results of ZeroFPR.

Optimization and Control 90C06, 90C25, 90C26, 90C53, 49J52, 49J53

Douglas-Rachford splitting and ADMM for nonconvex optimization: Accelerated and Newton-type linesearch algorithms

1 code implementation20 May 2020 Andreas Themelis, Lorenzo Stella, Panagiotis Patrinos

Although the performance of popular optimization algorithms such as Douglas-Rachford splitting (DRS) and the ADMM is satisfactory in small and well-scaled problems, ill conditioning and problem size pose a severe obstacle to their reliable employment.

Optimization and Control 90C06, 90C25, 90C26, 49J52, 49J53

Forward-backward quasi-Newton methods for nonsmooth optimization problems

2 code implementations27 Apr 2016 Lorenzo Stella, Andreas Themelis, Panagiotis Patrinos

We propose an algorithmic scheme that enjoys the same global convergence properties of FBS when the problem is convex, or when the objective function possesses the Kurdyka-{\L}ojasiewicz property at its critical points.

Optimization and Control

QPALM: A Proximal Augmented Lagrangian Method for Nonconvex Quadratic Programs

1 code implementation6 Oct 2020 Ben Hermans, Andreas Themelis, Panagiotis Patrinos

The resulting implementation is shown to be extremely robust in numerical simulations, solving all of the Maros-Meszaros problems and finding a stationary point for most of the nonconvex QPs in the Cutest test set.

Optimization and Control 90C05, 90C20, 90C26, 49J53, 49M15

Block-coordinate and incremental aggregated proximal gradient methods for nonsmooth nonconvex problems

3 code implementations24 Jun 2019 Puya Latafat, Andreas Themelis, Panagiotis Patrinos

This paper analyzes block-coordinate proximal gradient methods for minimizing the sum of a separable smooth function and a (nonseparable) nonsmooth function, both of which are allowed to be nonconvex.

Optimization and Control 90C06, 90C25, 90C26, 49J52, 49J53

Adaptive proximal algorithms for convex optimization under local Lipschitz continuity of the gradient

2 code implementations11 Jan 2023 Puya Latafat, Andreas Themelis, Lorenzo Stella, Panagiotis Patrinos

Backtracking linesearch is the de facto approach for minimizing continuously differentiable functions with locally Lipschitz gradient.

Tensor-based Multi-view Spectral Clustering via Shared Latent Space

1 code implementation23 Jul 2022 Qinghua Tao, Francesco Tonin, Panagiotis Patrinos, Johan A. K. Suykens

In our method, the dual variables, playing the role of hidden features, are shared by all views to construct a common latent space, coupling the views by learning projections from view-specific spaces.

Clustering

Deep Kernel Principal Component Analysis for Multi-level Feature Learning

1 code implementation22 Feb 2023 Francesco Tonin, Qinghua Tao, Panagiotis Patrinos, Johan A. K. Suykens

Principal Component Analysis (PCA) and its nonlinear extension Kernel PCA (KPCA) are widely used across science and industry for data analysis and dimensionality reduction.

Dimensionality Reduction

Extending Kernel PCA through Dualization: Sparsity, Robustness and Fast Algorithms

1 code implementation9 Jun 2023 Francesco Tonin, Alex Lambert, Panagiotis Patrinos, Johan A. K. Suykens

The goal of this paper is to revisit Kernel Principal Component Analysis (KPCA) through dualization of a difference of convex functions.

On the convergence of adaptive first order methods: proximal gradient and alternating minimization algorithms

1 code implementation30 Nov 2023 Puya Latafat, Andreas Themelis, Panagiotis Patrinos

Building upon recent works on linesearch-free adaptive proximal gradient methods, this paper proposes AdaPG$^{\pi, r}$, a framework that unifies and extends existing results by providing larger stepsize policies and improved lower bounds.

Multi-block Bregman proximal alternating linearized minimization and its application to orthogonal nonnegative matrix factorization

1 code implementation4 Aug 2019 Masoud Ahookhosh, Le Thi Khanh Hien, Nicolas Gillis, Panagiotis Patrinos

We introduce and analyze BPALM and A-BPALM, two multi-block proximal alternating linearized minimization algorithms using Bregman distances for solving structured nonconvex problems.

Optimization and Control Numerical Analysis Numerical Analysis

Inertial Block Proximal Methods for Non-Convex Non-Smooth Optimization

no code implementations ICML 2020 Le Thi Khanh Hien, Nicolas Gillis, Panagiotis Patrinos

We propose inertial versions of block coordinate descent methods for solving non-convex non-smooth composite optimization problems.

Bregman forward-backward splitting for nonconvex composite optimization: superlinear convergence to nonisolated critical points

1 code implementation28 May 2019 Masoud Ahookhosh, Andreas Themelis, Panagiotis Patrinos

We introduce Bella, a locally superlinearly convergent Bregman forward-backward splitting method for minimizing the sum of two nonconvex functions, one of which satisfying a relative smoothness condition and the other one possibly nonsmooth.

Optimization and Control 90C06, 90C25, 90C26, 49J52, 49J53

SuperMann: a superlinearly convergent algorithm for finding fixed points of nonexpansive operators

1 code implementation22 Sep 2016 Andreas Themelis, Panagiotis Patrinos

As a result, SuperMann enhances and robustifies all operator splitting schemes for structured convex optimization, overcoming their well known sensitivity to ill conditioning.

Optimization and Control 47H09, 90C25, 90C53, 65K15

Data-driven distributionally robust MPC for constrained stochastic systems

no code implementations4 Mar 2021 Peter Coppens, Panagiotis Patrinos

In this paper we introduce a novel approach to distributionally robust optimal control that supports online learning of the ambiguity set, while guaranteeing recursive feasibility.

Lasry-Lions Envelopes and Nonconvex Optimization: A Homotopy Approach

no code implementations15 Mar 2021 Miguel Simões, Andreas Themelis, Panagiotis Patrinos

Lasry-Lions envelopes can also be seen as an "intermediate" between a given function and its convex envelope, and we make use of this property to develop a method that builds a sequence of approximate subproblems that are easier to solve than the original problem.

Block Alternating Bregman Majorization Minimization with Extrapolation

1 code implementation9 Jul 2021 Le Thi Khanh Hien, Duy Nhat Phan, Nicolas Gillis, Masoud Ahookhosh, Panagiotis Patrinos

In this paper, we consider a class of nonsmooth nonconvex optimization problems whose objective is the sum of a block relative smooth function and a proper and lower semicontinuous block separable function.

Safe, Learning-Based MPC for Highway Driving under Lane-Change Uncertainty: A Distributionally Robust Approach

no code implementations27 Jun 2022 Mathijs Schuurmans, Alexander Katriniok, Christopher Meissen, H. Eric Tseng, Panagiotis Patrinos

We present a case study applying learning-based distributionally robust model predictive control to highway motion planning under stochastic uncertainty of the lane change behavior of surrounding road users.

Model Predictive Control Motion Planning

SPIRAL: A superlinearly convergent incremental proximal algorithm for nonconvex finite sum minimization

no code implementations17 Jul 2022 Pourya Behmandpoor, Puya Latafat, Andreas Themelis, Marc Moonen, Panagiotis Patrinos

We introduce SPIRAL, a SuPerlinearly convergent Incremental pRoximal ALgorithm, for solving nonconvex regularized finite sum problems under a relative smoothness assumption.

Sim2real for Autonomous Vehicle Control using Executable Digital Twin

no code implementations12 Aug 2022 Jean Pierre Allamaa, Panagiotis Patrinos, Herman Van der Auweraer, Tong Duy Son

In this work, we propose a sim2real method to transfer and adapt a nonlinear model predictive controller (NMPC) from simulation to the real target system based on executable digital twin (xDT).

Solving stochastic weak Minty variational inequalities without increasing batch size

1 code implementation17 Feb 2023 Thomas Pethick, Olivier Fercoq, Puya Latafat, Panagiotis Patrinos, Volkan Cevher

This paper introduces a family of stochastic extragradient-type algorithms for a class of nonconvex-nonconcave problems characterized by the weak Minty variational inequality (MVI).

Distributionally Robust Optimization using Cost-Aware Ambiguity Sets

no code implementations16 Mar 2023 Mathijs Schuurmans, Panagiotis Patrinos

We present a novel framework for distributionally robust optimization (DRO), called cost-aware DRO (CADRO).

Nonlinear SVD with Asymmetric Kernels: feature learning and asymmetric Nyström method

no code implementations12 Jun 2023 Qinghua Tao, Francesco Tonin, Panagiotis Patrinos, Johan A. K. Suykens

We describe a nonlinear extension of the matrix Singular Value Decomposition through asymmetric kernels, namely KSVD.

Combining Primal and Dual Representations in Deep Restricted Kernel Machines Classifiers

no code implementations12 Jun 2023 Francesco Tonin, Panagiotis Patrinos, Johan A. K. Suykens

In the context of deep learning with kernel machines, the deep Restricted Kernel Machine (DRKM) framework allows multiple levels of kernel PCA (KPCA) and Least-Squares Support Vector Machines (LSSVM) to be combined into a deep architecture using visible and hidden units.

Classification

Zeroth-order Asynchronous Learning with Bounded Delays with a Use-case in Resource Allocation in Communication Networks

no code implementations8 Nov 2023 Pourya Behmandpoor, Marc Moonen, Panagiotis Patrinos

Distributed optimization has experienced a significant surge in interest due to its wide-ranging applications in distributed learning and adaptation.

Distributed Optimization

A Deep Learning Based Resource Allocator for Communication Systems with Dynamic User Utility Demands

no code implementations8 Nov 2023 Pourya Behmandpoor, Panagiotis Patrinos, Marc Moonen

The optimization algorithm aims to optimize the on-off status of users in a time-sharing problem to satisfy their utility demands in expectation.

Fast data-driven iterative learning control for linear system with output disturbance

no code implementations21 Dec 2023 Jia Wang, Leander Hemelhof, Ivan Markovsky, Panagiotis Patrinos

This paper studies data-driven iterative learning control (ILC) for linear time-invariant (LTI) systems with unknown dynamics, output disturbances and input box-constraints.

Real-time MPC with Control Barrier Functions for Autonomous Driving using Safety Enhanced Collocation

no code implementations12 Jan 2024 Jean Pierre Allamaa, Panagiotis Patrinos, Toshiyuki Ohtsuka, Tong Duy Son

The autonomous driving industry is continuously dealing with more safety-critical scenarios, and nonlinear model predictive control (NMPC) is a powerful control strategy for handling such situations.

Autonomous Driving Model Predictive Control

Adaptive proximal gradient methods are universal without approximation

no code implementations9 Feb 2024 Konstantinos A. Oikonomidis, Emanuel Laude, Puya Latafat, Andreas Themelis, Panagiotis Patrinos

We show that adaptive proximal gradient methods for convex problems are not restricted to traditional Lipschitzian assumptions.

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