Don't Be Greedy, Just Relax! Pruning LLMs via Frank-Wolfe

Fuente: arXiv
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Main Authors: Roux, Christophe, Zimmer, Max, d'Aspremont, Alexandre, Pokutta, Sebastian
Format: Preprint
Published: 2025
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author Roux, Christophe
Zimmer, Max
d'Aspremont, Alexandre
Pokutta, Sebastian
author_facet Roux, Christophe
Zimmer, Max
d'Aspremont, Alexandre
Pokutta, Sebastian
contents Pruning is a common technique to reduce the compute and storage requirements of Neural Networks. While conventional approaches typically retrain the model to recover pruning-induced performance degradation, state-of-the-art Large Language Model (LLM) pruning methods operate layer-wise, minimizing the per-layer pruning error on a small calibration dataset to avoid full retraining, which is considered computationally prohibitive for LLMs. However, finding the optimal pruning mask is a hard combinatorial problem and solving it to optimality is intractable. Existing methods hence rely on greedy heuristics that ignore the weight interactions in the pruning objective. In this work, we instead consider the convex relaxation of these combinatorial constraints and solve the resulting problem using the Frank-Wolfe (FW) algorithm. Our method drastically reduces the per-layer pruning error, outperforms strong baselines on state-of-the-art GPT architectures, and remains memory-efficient. We provide theoretical justification by showing that, combined with the convergence guarantees of the FW algorithm, we obtain an approximate solution to the original combinatorial problem upon rounding the relaxed solution to integrality.
format Preprint
id arxiv_https___arxiv_org_abs_2510_13713
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Don't Be Greedy, Just Relax! Pruning LLMs via Frank-Wolfe
Roux, Christophe
Zimmer, Max
d'Aspremont, Alexandre
Pokutta, Sebastian
Machine Learning
Optimization and Control
Pruning is a common technique to reduce the compute and storage requirements of Neural Networks. While conventional approaches typically retrain the model to recover pruning-induced performance degradation, state-of-the-art Large Language Model (LLM) pruning methods operate layer-wise, minimizing the per-layer pruning error on a small calibration dataset to avoid full retraining, which is considered computationally prohibitive for LLMs. However, finding the optimal pruning mask is a hard combinatorial problem and solving it to optimality is intractable. Existing methods hence rely on greedy heuristics that ignore the weight interactions in the pruning objective. In this work, we instead consider the convex relaxation of these combinatorial constraints and solve the resulting problem using the Frank-Wolfe (FW) algorithm. Our method drastically reduces the per-layer pruning error, outperforms strong baselines on state-of-the-art GPT architectures, and remains memory-efficient. We provide theoretical justification by showing that, combined with the convergence guarantees of the FW algorithm, we obtain an approximate solution to the original combinatorial problem upon rounding the relaxed solution to integrality.
title Don't Be Greedy, Just Relax! Pruning LLMs via Frank-Wolfe
topic Machine Learning
Optimization and Control
url https://arxiv.org/abs/2510.13713