Safe-EF: Error Feedback for Nonsmooth Constrained Optimization

Fuente: arXiv
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Main Authors: Islamov, Rustem, As, Yarden, Fatkhullin, Ilyas
Format: Preprint
Published: 2025
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author Islamov, Rustem
As, Yarden
Fatkhullin, Ilyas
author_facet Islamov, Rustem
As, Yarden
Fatkhullin, Ilyas
contents Federated learning faces severe communication bottlenecks due to the high dimensionality of model updates. Communication compression with contractive compressors (e.g., Top-K) is often preferable in practice but can degrade performance without proper handling. Error feedback (EF) mitigates such issues but has been largely restricted for smooth, unconstrained problems, limiting its real-world applicability where non-smooth objectives and safety constraints are critical. We advance our understanding of EF in the canonical non-smooth convex setting by establishing new lower complexity bounds for first-order algorithms with contractive compression. Next, we propose Safe-EF, a novel algorithm that matches our lower bound (up to a constant) while enforcing safety constraints essential for practical applications. Extending our approach to the stochastic setting, we bridge the gap between theory and practical implementation. Extensive experiments in a reinforcement learning setup, simulating distributed humanoid robot training, validate the effectiveness of Safe-EF in ensuring safety and reducing communication complexity.
format Preprint
id arxiv_https___arxiv_org_abs_2505_06053
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Safe-EF: Error Feedback for Nonsmooth Constrained Optimization
Islamov, Rustem
As, Yarden
Fatkhullin, Ilyas
Machine Learning
Optimization and Control
Federated learning faces severe communication bottlenecks due to the high dimensionality of model updates. Communication compression with contractive compressors (e.g., Top-K) is often preferable in practice but can degrade performance without proper handling. Error feedback (EF) mitigates such issues but has been largely restricted for smooth, unconstrained problems, limiting its real-world applicability where non-smooth objectives and safety constraints are critical. We advance our understanding of EF in the canonical non-smooth convex setting by establishing new lower complexity bounds for first-order algorithms with contractive compression. Next, we propose Safe-EF, a novel algorithm that matches our lower bound (up to a constant) while enforcing safety constraints essential for practical applications. Extending our approach to the stochastic setting, we bridge the gap between theory and practical implementation. Extensive experiments in a reinforcement learning setup, simulating distributed humanoid robot training, validate the effectiveness of Safe-EF in ensuring safety and reducing communication complexity.
title Safe-EF: Error Feedback for Nonsmooth Constrained Optimization
topic Machine Learning
Optimization and Control
url https://arxiv.org/abs/2505.06053