Restricting weight updates to non-principal subspace preserves old skills while learning new ones

Subspace Tuning (SST) protects the top 99% of singular directions, matches target-task accuracy, and nearly eliminates forgetting in large models across multiple domains.

Big Tech
Arnav Chavan · Kusha Sareen · Rishabh Tiwari · Abhranil Chandra · Johan Obando-Ceron · Kurt Keutzer · +3 more

UC Berkeley · Mila · McGill University · UMass Amherst · Université de Montréal

Research Digest··2 min read
Chavan et al.

The authors propose SST, which projects the final optimizer update (rather than the raw gradient) onto the complement of the top-k singular subspace of each weight matrix.

Why this paper

From Google and 7 others

In one line

Subspace Tuning prevents catastrophic forgetting by restricting LLM fine-tuning updates to non principal weight subspaces.

What we could check

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  • ✓Limitations stated by the authors (2 noted)
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