Search Results for author: Mikael Johansson

Found 28 papers, 2 papers with code

Differentially Private Online Federated Learning with Correlated Noise

no code implementations25 Mar 2024 Jiaojiao Zhang, Linglingzhi Zhu, Mikael Johansson

We propose a novel differentially private algorithm for online federated learning that employs temporally correlated noise to improve the utility while ensuring the privacy of the continuously released models.

Federated Learning

Asynchronous Distributed Optimization with Delay-free Parameters

no code implementations11 Dec 2023 Xuyang Wu, Changxin Liu, Sindri Magnusson, Mikael Johansson

In contrast to alternatives, our algorithms can converge to the fixed point set of their synchronous counterparts using step-sizes that are independent of the delays.

Distributed Optimization

Composite federated learning with heterogeneous data

no code implementations4 Sep 2023 Jiaojiao Zhang, Jiang Hu, Mikael Johansson

We propose a novel algorithm for solving the composite Federated Learning (FL) problem.

Federated Learning

Dynamic Privacy Allocation for Locally Differentially Private Federated Learning with Composite Objectives

no code implementations2 Aug 2023 Jiaojiao Zhang, Dominik Fay, Mikael Johansson

This paper proposes a locally differentially private federated learning algorithm for strongly convex but possibly nonsmooth problems that protects the gradients of each worker against an honest but curious server.

Federated Learning

Delay-adaptive step-sizes for asynchronous learning

no code implementations17 Feb 2022 Xuyang Wu, Sindri Magnusson, Hamid Reza Feyzmahdavian, Mikael Johansson

In this paper, we show that it is possible to use learning rates that depend on the actual time-varying delays in the system.

On Uniform Boundedness Properties of SGD and its Momentum Variants

no code implementations25 Jan 2022 Xiaoyu Wang, Mikael Johansson

In this note, we investigate uniform boundedness properties of iterates and function values along the trajectories of the stochastic gradient descent algorithm and its important momentum variant.

regression Retrieval

Asynchronous Iterations in Optimization: New Sequence Results and Sharper Algorithmic Guarantees

no code implementations9 Sep 2021 Hamid Reza Feyzmahdavian, Mikael Johansson

We introduce novel convergence results for asynchronous iterations that appear in the analysis of parallel and distributed optimization algorithms.

Distributed Optimization

Bandwidth-based Step-Sizes for Non-Convex Stochastic Optimization

no code implementations5 Jun 2021 Xiaoyu Wang, Mikael Johansson

Many popular learning-rate schedules for deep neural networks combine a decaying trend with local perturbations that attempt to escape saddle points and bad local minima.

Stochastic Optimization

On the Convergence of Step Decay Step-Size for Stochastic Optimization

no code implementations NeurIPS 2021 Xiaoyu Wang, Sindri Magnússon, Mikael Johansson

The convergence of stochastic gradient descent is highly dependent on the step-size, especially on non-convex problems such as neural network training.

Stochastic Optimization

Stability and Convergence of Stochastic Gradient Clipping: Beyond Lipschitz Continuity and Smoothness

no code implementations12 Feb 2021 Vien V. Mai, Mikael Johansson

We also study the convergence of a clipped method with momentum, which includes clipped SGD as a special case, for weakly convex problems under standard assumptions.

Advances in Asynchronous Parallel and Distributed Optimization

no code implementations24 Jun 2020 Mahmoud Assran, Arda Aytekin, Hamid Feyzmahdavian, Mikael Johansson, Michael Rabbat

Motivated by large-scale optimization problems arising in the context of machine learning, there have been several advances in the study of asynchronous parallel and distributed optimization methods during the past decade.

Distributed Optimization

A flexible framework for communication-efficient machine learning: from HPC to IoT

no code implementations13 Mar 2020 Sarit Khirirat, Sindri Magnússon, Arda Aytekin, Mikael Johansson

With the increasing scale of machine learning tasks, it has become essential to reduce the communication between computing nodes.

BIG-bench Machine Learning

Convergence of a Stochastic Gradient Method with Momentum for Non-Smooth Non-Convex Optimization

no code implementations ICML 2020 Vien V. Mai, Mikael Johansson

This paper establishes the convergence rate of a stochastic subgradient method with a momentum term of Polyak type for a broad class of non-smooth, non-convex, and constrained optimization problems.

Anderson Acceleration of Proximal Gradient Methods

1 code implementation ICML 2020 Vien V. Mai, Mikael Johansson

We therefore propose a simple scheme for stabilization that combines the global worst-case guarantees of proximal gradient methods with the local adaptation and practical speed-up of Anderson acceleration.

Efficient Stochastic Programming in Julia

1 code implementation23 Sep 2019 Martin Biel, Mikael Johansson

These structure-exploiting solvers are based on variations of the classical L-shaped and progressive-hedging algorithms.

Optimization and Control Mathematical Software 90C15, 90C06, 90C90

Compressed Gradient Methods with Hessian-Aided Error Compensation

no code implementations23 Sep 2019 Sarit Khirirat, Sindri Magnússon, Mikael Johansson

Several gradient compression techniques have been proposed to reduce the communication load at the price of a loss in solution accuracy.

Noisy Accelerated Power Method for Eigenproblems with Applications

no code implementations20 Mar 2019 Vien V. Mai, Mikael Johansson

This paper introduces an efficient algorithm for finding the dominant generalized eigenvectors of a pair of symmetric matrices.

Curvature-Exploiting Acceleration of Elastic Net Computations

no code implementations24 Jan 2019 Vien V. Mai, Mikael Johansson

This paper introduces an efficient second-order method for solving the elastic net problem.

Harnessing the Power of Serverless Runtimes for Large-Scale Optimization

no code implementations10 Jan 2019 Arda Aytekin, Mikael Johansson

The event-driven and elastic nature of serverless runtimes makes them a very efficient and cost-effective alternative for scaling up computations.

regression

POLO: a POLicy-based Optimization library

no code implementations8 Oct 2018 Arda Aytekin, Martin Biel, Mikael Johansson

We present POLO --- a C++ library for large-scale parallel optimization research that emphasizes ease-of-use, flexibility and efficiency in algorithm design.

The Convergence of Sparsified Gradient Methods

no code implementations NeurIPS 2018 Dan Alistarh, Torsten Hoefler, Mikael Johansson, Sarit Khirirat, Nikola Konstantinov, Cédric Renggli

Distributed training of massive machine learning models, in particular deep neural networks, via Stochastic Gradient Descent (SGD) is becoming commonplace.

Quantization

Distributed learning with compressed gradients

no code implementations18 Jun 2018 Sarit Khirirat, Hamid Reza Feyzmahdavian, Mikael Johansson

Asynchronous computation and gradient compression have emerged as two key techniques for achieving scalability in distributed optimization for large-scale machine learning.

BIG-bench Machine Learning Distributed Optimization

Continuous-time Value Function Approximation in Reproducing Kernel Hilbert Spaces

no code implementations NeurIPS 2018 Motoya Ohnishi, Masahiro Yukawa, Mikael Johansson, Masashi Sugiyama

Motivated by the success of reinforcement learning (RL) for discrete-time tasks such as AlphaGo and Atari games, there has been a recent surge of interest in using RL for continuous-time control of physical systems (cf.

Atari Games Gaussian Processes +2

Analysis and Implementation of an Asynchronous Optimization Algorithm for the Parameter Server

no code implementations18 Oct 2016 Arda Aytekin, Hamid Reza Feyzmahdavian, Mikael Johansson

This paper presents an asynchronous incremental aggregated gradient algorithm and its implementation in a parameter server framework for solving regularized optimization problems.

Optimal Radio Frequency Energy Harvesting with Limited Energy Arrival Knowledge

no code implementations2 Aug 2015 Zhenhua Zou, Anders Gidmark, Themistoklis Charalambous, Mikael Johansson

While the idea of RF-EH is appealing, it is not always beneficial to attempt to harvest energy; in environments where the ambient energy is low, nodes could consume more energy being awake with their harvesting circuits turned on than what they can extract from the ambient radio signals; it is then better to enter a sleep mode until the ambient RF energy increases.

Stochastic Online Shortest Path Routing: The Value of Feedback

no code implementations27 Sep 2013 M. Sadegh Talebi, Zhenhua Zou, Richard Combes, Alexandre Proutiere, Mikael Johansson

The parameters, and hence the optimal path, can only be estimated by routing packets through the network and observing the realized delays.

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