Provable Learning of Random Hierarchy Models and Hierarchical Shallow-to-Deep Chaining

Fuente: arXiv
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Main Authors: Ren, Yunwei, Dandi, Yatin, Krzakala, Florent, Lee, Jason D.
Format: Preprint
Published: 2026
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author Ren, Yunwei
Dandi, Yatin
Krzakala, Florent
Lee, Jason D.
author_facet Ren, Yunwei
Dandi, Yatin
Krzakala, Florent
Lee, Jason D.
contents The empirical success of deep learning is often attributed to deep networks' ability to exploit hierarchical structure in data, constructing increasingly complex features across layers. Yet despite substantial progress in deep learning theory, most optimization results sill focus on networks with only two or three layers, leaving the theoretical understanding of hierarchical learning in genuinely deep models limited. This leads to a natural question: can we prove that deep networks, trained by gradient-based methods, can efficiently exploit hierarchical structure? In this work, we consider Random Hierarchy Models -- a hierarchical context-free grammar introduced by arXiv:2307.02129 and conjectured to separate deep and shallow networks. We prove that, under mild conditions, a deep convolutional network can be efficiently trained to learn this function class. Our proof builds on a general observation: if intermediate layers can receive clean signal from the labels and the relevant features are weakly identifiable, then layerwise training each individual layer suffices to hierarchically learn the target function.
format Preprint
id arxiv_https___arxiv_org_abs_2601_19756
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Provable Learning of Random Hierarchy Models and Hierarchical Shallow-to-Deep Chaining
Ren, Yunwei
Dandi, Yatin
Krzakala, Florent
Lee, Jason D.
Machine Learning
The empirical success of deep learning is often attributed to deep networks' ability to exploit hierarchical structure in data, constructing increasingly complex features across layers. Yet despite substantial progress in deep learning theory, most optimization results sill focus on networks with only two or three layers, leaving the theoretical understanding of hierarchical learning in genuinely deep models limited. This leads to a natural question: can we prove that deep networks, trained by gradient-based methods, can efficiently exploit hierarchical structure? In this work, we consider Random Hierarchy Models -- a hierarchical context-free grammar introduced by arXiv:2307.02129 and conjectured to separate deep and shallow networks. We prove that, under mild conditions, a deep convolutional network can be efficiently trained to learn this function class. Our proof builds on a general observation: if intermediate layers can receive clean signal from the labels and the relevant features are weakly identifiable, then layerwise training each individual layer suffices to hierarchically learn the target function.
title Provable Learning of Random Hierarchy Models and Hierarchical Shallow-to-Deep Chaining
topic Machine Learning
url https://arxiv.org/abs/2601.19756