A Hierarchical Sampling Framework for bounding the Generalization Error of Federated Learning

Fuente: arXiv
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Main Authors: Filatrella, Dario, Thobaben, Ragnar, Skoglund, Mikael
Format: Preprint
Published: 2026
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author Filatrella, Dario
Thobaben, Ragnar
Skoglund, Mikael
author_facet Filatrella, Dario
Thobaben, Ragnar
Skoglund, Mikael
contents We study expected generalization bounds for the Hierarchical Federated Learning (HFL) setup using Wasserstein distance. We introduce a generalized framework in which data is sampled hierarchically, and we model it with a multi-layered tree structure that induces dependencies among the clients' datasets. We derive generalization bounds in terms of Wasserstein distance under the Lipschitz assumption on the loss function, by applying a supersample construction that allows us to measure the sensitivity of the algorithm to the change of a single node in the sampling tree. By leveraging the FL structure, we recover and strictly imply existing state-of-the-art conditional mutual information (CMI) bounds in the case of bounded losses. We also show that our bound can be applied together with Differential Privacy assumptions, to recover generalization bounds based on algorithmic privacy. To assess the tightness of our bounds, we study the Gaussian Location Model (GLM) and show that we recover the actual asymptotic rate of the generalization error.
format Preprint
id arxiv_https___arxiv_org_abs_2605_03499
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle A Hierarchical Sampling Framework for bounding the Generalization Error of Federated Learning
Filatrella, Dario
Thobaben, Ragnar
Skoglund, Mikael
Machine Learning
Information Theory
We study expected generalization bounds for the Hierarchical Federated Learning (HFL) setup using Wasserstein distance. We introduce a generalized framework in which data is sampled hierarchically, and we model it with a multi-layered tree structure that induces dependencies among the clients' datasets. We derive generalization bounds in terms of Wasserstein distance under the Lipschitz assumption on the loss function, by applying a supersample construction that allows us to measure the sensitivity of the algorithm to the change of a single node in the sampling tree. By leveraging the FL structure, we recover and strictly imply existing state-of-the-art conditional mutual information (CMI) bounds in the case of bounded losses. We also show that our bound can be applied together with Differential Privacy assumptions, to recover generalization bounds based on algorithmic privacy. To assess the tightness of our bounds, we study the Gaussian Location Model (GLM) and show that we recover the actual asymptotic rate of the generalization error.
title A Hierarchical Sampling Framework for bounding the Generalization Error of Federated Learning
topic Machine Learning
Information Theory
url https://arxiv.org/abs/2605.03499