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Pretraining data scale reverses Muon-AdamW fine-tuning gap

Original title: Pretraining Data Scale Reverses the Muon-AdamW Fine-Tuning Gap

arXiv cs.AI / cs.LG / cs.CLby Catherine Li ()1 min read
AI summary · x-ai/grok-4.7Summaries by Vani AI

Beyond large pretraining budgets AdamW outperforms Muon after fine-tuning with the gap widening as model size grows.

Muon offers speedup over AdamW in minimizing pretraining loss but its advantage disappears after fine-tuning when data budgets are large. As model size increases AdamW overtakes Muon at progressively smaller token-parameter ratios. The reversal is explained via the margin-to-spread ratio measuring logit separation relative to spread in language models.

Key facts
  • AdamW outperforms Muon post fine-tuning
  • Gap appears at large pretraining budgets
  • Scale-dependent crossover point
  • Explained by margin-to-spread ratio analysis
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From the original article

1 min read at arxiv.org

Muon has recently emerged as a promising optimizer for pretraining large language models, offering a speedup over AdamW in minimizing pretraining loss. However, it remains unclear whether Muon's advantage persists after fine-tuning.

arXiv cs.AI / cs.LG / cs.CL

By Catherine Li · arxiv.org

Read the full article at arXiv cs.AI / cs.LG / cs.CL

A short excerpt; the article and its images belong to the publisher. Summary, key facts and assessment above are AI-written from the article and can be wrong.