1 code implementation • 4 Mar 2025 • Dimitris Oikonomou, Nicolas Loizou
Sharpness-Aware Minimization (SAM) has emerged as a powerful method for improving generalization in machine learning models by minimizing the sharpness of the loss landscape.
no code implementations • 14 Jan 2025 • Taeho Yoon, Sayantan Choudhury, Nicolas Loizou
Traditional Federated Learning (FL) approaches assume collaborative clients with aligned objectives working towards a shared global model.
1 code implementation • 6 Jun 2024 • Dimitris Oikonomou, Nicolas Loizou
Our convergence analysis of SHB is tight and obtains the convergence guarantees of stochastic Polyak step-size for SGD as a special case.
no code implementations • 14 Mar 2024 • Tianqi Zheng, Nicolas Loizou, Pengcheng You, Enrique Mallada
Gradient Descent Ascent (GDA) methods for min-max optimization problems typically produce oscillatory behavior that can lead to instability, e. g., in bilinear settings.
1 code implementation • 11 Mar 2024 • Konstantinos Emmanouilidis, René Vidal, Nicolas Loizou
The Stochastic Extragradient (SEG) method is one of the most popular algorithms for solving finite-sum min-max optimization and variational inequality problems (VIPs) appearing in various machine learning tasks.
1 code implementation • 5 Mar 2024 • Sayantan Choudhury, Nazarii Tupitsa, Nicolas Loizou, Samuel Horvath, Martin Takac, Eduard Gorbunov
Adaptive methods are extremely popular in machine learning as they make learning rate tuning less expensive.
1 code implementation • 12 Jul 2023 • Sohom Mukherjee, Nicolas Loizou, Sebastian U. Stich
In this work, we propose locally adaptive federated learning algorithms, that leverage the local geometric information for each client function.
1 code implementation • 8 Jun 2023 • Siqi Zhang, Sayantan Choudhury, Sebastian U Stich, Nicolas Loizou
However, with the increase of minimax optimization and variational inequality problems in machine learning, the necessity of designing efficient distributed/federated learning approaches for these problems is becoming more apparent.
1 code implementation • NeurIPS 2023 • Sayantan Choudhury, Eduard Gorbunov, Nicolas Loizou
In addition, several important questions regarding the convergence properties of these methods are still open, including mini-batching, efficient step-size selection, and convergence guarantees under different sampling strategies.
3 code implementations • 12 Jun 2022 • Samuel Sokota, Ryan D'Orazio, J. Zico Kolter, Nicolas Loizou, Marc Lanctot, Ioannis Mitliagkas, Noam Brown, Christian Kroer
This work studies an algorithm, which we call magnetic mirror descent, that is inspired by mirror descent and the non-Euclidean proximal gradient algorithm.
1 code implementation • 15 Feb 2022 • Aleksandr Beznosikov, Eduard Gorbunov, Hugo Berard, Nicolas Loizou
Although variants of the new methods are known for solving minimization problems, they were never considered or analyzed for solving min-max problems and VIPs.
1 code implementation • 16 Nov 2021 • Eduard Gorbunov, Hugo Berard, Gauthier Gidel, Nicolas Loizou
The Stochastic Extragradient (SEG) method is one of the most popular algorithms for solving min-max optimization and variational inequalities problems (VIP) appearing in various machine learning tasks.
no code implementations • 28 Oct 2021 • Ryan D'Orazio, Nicolas Loizou, Issam Laradji, Ioannis Mitliagkas
We investigate the convergence of stochastic mirror descent (SMD) under interpolation in relatively smooth and smooth convex optimization.
1 code implementation • 8 Oct 2021 • Eduard Gorbunov, Nicolas Loizou, Gauthier Gidel
In this paper, we resolve one of such questions and derive the first last-iterate $O(1/K)$ convergence rate for EG for monotone and Lipschitz VIP without any additional assumptions on the operator unlike the only known result of this type (Golowich et al., 2020) that relies on the Lipschitzness of the Jacobian of the operator.
no code implementations • 30 Jun 2021 • Chris Junchi Li, Yaodong Yu, Nicolas Loizou, Gauthier Gidel, Yi Ma, Nicolas Le Roux, Michael I. Jordan
We study the stochastic bilinear minimax optimization problem, presenting an analysis of the same-sample Stochastic ExtraGradient (SEG) method with constant step size, and presenting variations of the method that yield favorable convergence.
1 code implementation • NeurIPS 2021 • Nicolas Loizou, Hugo Berard, Gauthier Gidel, Ioannis Mitliagkas, Simon Lacoste-Julien
Two of the most prominent algorithms for solving unconstrained smooth games are the classical stochastic gradient descent-ascent (SGDA) and the recently introduced stochastic consensus optimization (SCO) [Mescheder et al., 2017].
no code implementations • 19 Feb 2021 • Zheng Shi, Abdurakhmon Sadiev, Nicolas Loizou, Peter Richtárik, Martin Takáč
We present AI-SARAH, a practical variant of SARAH.
no code implementations • ICML 2020 • Nicolas Loizou, Hugo Berard, Alexia Jolicoeur-Martineau, Pascal Vincent, Simon Lacoste-Julien, Ioannis Mitliagkas
The success of adversarial formulations in machine learning has brought renewed motivation for smooth games.
no code implementations • 20 Jun 2020 • Ahmed Khaled, Othmane Sebbouh, Nicolas Loizou, Robert M. Gower, Peter Richtárik
We showcase this by obtaining a simple formula for the optimal minibatch size of two variance reduced methods (\textit{L-SVRG} and \textit{SAGA}).
no code implementations • 18 Jun 2020 • Robert M. Gower, Othmane Sebbouh, Nicolas Loizou
Stochastic Gradient Descent (SGD) is being used routinely for optimizing non-convex functions.
no code implementations • ICML 2020 • Anastasia Koloskova, Nicolas Loizou, Sadra Boreiri, Martin Jaggi, Sebastian U. Stich
Decentralized stochastic optimization methods have gained a lot of attention recently, mainly because of their cheap per iteration cost, data locality, and their communication-efficiency.
1 code implementation • 24 Feb 2020 • Nicolas Loizou, Sharan Vaswani, Issam Laradji, Simon Lacoste-Julien
Consequently, the proposed stochastic Polyak step-size (SPS) is an attractive choice for setting the learning rate for stochastic gradient descent (SGD).
no code implementations • 26 Sep 2019 • Nicolas Loizou
In the era of big data, one of the key challenges is the development of novel optimization algorithms that can accommodate vast amounts of data while at the same time satisfying constraints and limitations of the problem under study.
no code implementations • 20 May 2019 • Nicolas Loizou, Peter Richtárik
In this work we present a new framework for the analysis and design of randomized gossip algorithms for solving the average consensus problem.
no code implementations • 19 Mar 2019 • Nicolas Loizou, Peter Richtárik
We relax this requirement by allowing for the sub-problem to be solved inexactly.
no code implementations • 27 Jan 2019 • Robert Mansel Gower, Nicolas Loizou, Xun Qian, Alibek Sailanbayev, Egor Shulgin, Peter Richtarik
By specializing our theorem to different mini-batching strategies, such as sampling with replacement and independent sampling, we derive exact expressions for the stepsize as a function of the mini-batch size.
no code implementations • 27 Jan 2019 • Filip Hanzely, Jakub Konečný, Nicolas Loizou, Peter Richtárik, Dmitry Grishchenko
In this work we present a randomized gossip algorithm for solving the average consensus problem while at the same time protecting the information about the initial private values stored at the nodes.
3 code implementations • ICLR 2019 • Mahmoud Assran, Nicolas Loizou, Nicolas Ballas, Michael Rabbat
Distributed data-parallel algorithms aim to accelerate the training of deep neural networks by parallelizing the computation of large mini-batch gradient updates across multiple nodes.
no code implementations • 31 Oct 2018 • Nicolas Loizou, Michael Rabbat, Peter Richtárik
In this work we present novel provably accelerated gossip algorithms for solving the average consensus problem.
no code implementations • 23 Sep 2018 • Nicolas Loizou, Peter Richtárik
In this paper we show how the stochastic heavy ball method (SHB) -- a popular method for solving stochastic convex and non-convex optimization problems --operates as a randomized gossip algorithm.
no code implementations • 27 Dec 2017 • Nicolas Loizou, Peter Richtárik
We prove linear convergence of several stochastic methods with stochastic momentum, and show that in some sparse data regimes and for sufficiently small momentum parameters, these methods enjoy better overall complexity than methods with deterministic momentum.
no code implementations • 30 Oct 2017 • Nicolas Loizou, Peter Richtárik
In this work we establish the first linear convergence result for the stochastic heavy ball method.
no code implementations • 23 Jun 2017 • Filip Hanzely, Jakub Konečný, Nicolas Loizou, Peter Richtárik, Dmitry Grishchenko
In this work we present three different randomized gossip algorithms for solving the average consensus problem while at the same time protecting the information about the initial private values stored at the nodes.
Optimization and Control