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Bibliographic Details
Main Author: Patel, Kumar Kshitij
Format: Preprint
Published: 2025
Subjects:
Online Access:https://arxiv.org/abs/2507.00195
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author Patel, Kumar Kshitij
author_facet Patel, Kumar Kshitij
contents This thesis contributes to the theoretical understanding of local update algorithms, especially Local SGD, in distributed and federated optimization under realistic models of data heterogeneity. A central focus is on the bounded second-order heterogeneity assumption, which is shown to be both necessary and sufficient for local updates to outperform centralized or mini-batch methods in convex and non-convex settings. The thesis establishes tight upper and lower bounds in several regimes for various local update algorithms and characterizes the min-max complexity of multiple problem classes. At its core is a fine-grained consensus-error-based analysis framework that yields sharper finite-time convergence bounds under third-order smoothness and relaxed heterogeneity assumptions. The thesis also extends to online federated learning, providing fundamental regret bounds under both first-order and bandit feedback. Together, these results clarify when and why local updates offer provable advantages, and the thesis serves as a self-contained guide for analyzing Local SGD in heterogeneous environments.
format Preprint
id arxiv_https___arxiv_org_abs_2507_00195
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle What Makes Local Updates Effective: The Role of Data Heterogeneity and Smoothness
Patel, Kumar Kshitij
Machine Learning
Artificial Intelligence
Multiagent Systems
Optimization and Control
This thesis contributes to the theoretical understanding of local update algorithms, especially Local SGD, in distributed and federated optimization under realistic models of data heterogeneity. A central focus is on the bounded second-order heterogeneity assumption, which is shown to be both necessary and sufficient for local updates to outperform centralized or mini-batch methods in convex and non-convex settings. The thesis establishes tight upper and lower bounds in several regimes for various local update algorithms and characterizes the min-max complexity of multiple problem classes. At its core is a fine-grained consensus-error-based analysis framework that yields sharper finite-time convergence bounds under third-order smoothness and relaxed heterogeneity assumptions. The thesis also extends to online federated learning, providing fundamental regret bounds under both first-order and bandit feedback. Together, these results clarify when and why local updates offer provable advantages, and the thesis serves as a self-contained guide for analyzing Local SGD in heterogeneous environments.
title What Makes Local Updates Effective: The Role of Data Heterogeneity and Smoothness
topic Machine Learning
Artificial Intelligence
Multiagent Systems
Optimization and Control
url https://arxiv.org/abs/2507.00195