ProcrustesGPT: Compressing LLMs with Structured Matrices and Orthogonal Transformations

Ekaterina Grishina, Mikhail Gorbunov, Maxim Rakhuba


Abstract
Large language models (LLMs) demonstrate impressive results in natural language processing tasks but require a significant amount of computational and memory resources. Structured matrix representations are a promising way for reducing the number of parameters of these models. However, it seems unrealistic to expect that weight matrices of pretrained models can be accurately represented by structured matrices without any fine-tuning.To overcome this issue, we utilize the fact that LLM output is invariant under certain orthogonal transformations of weight matrices.This insight can be leveraged to identify transformations that significantly improve the compressibility of weights within structured classes.The proposed approach is applicable to various types of structured matrices that support efficient projection operations. Code is available at: https://github.com/GrishKate/ProcrustesGPT.
Anthology ID:
2025.findings-acl.1381
Volume:
Findings of the Association for Computational Linguistics: ACL 2025
Month:
July
Year:
2025
Address:
Vienna, Austria
Editors:
Wanxiang Che, Joyce Nabende, Ekaterina Shutova, Mohammad Taher Pilehvar
Venue:
Findings
SIG:
Publisher:
Association for Computational Linguistics
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Pages:
26937–26949
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URL:
https://preview.aclanthology.org/display_plenaries/2025.findings-acl.1381/
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Bibkey:
Cite (ACL):
Ekaterina Grishina, Mikhail Gorbunov, and Maxim Rakhuba. 2025. ProcrustesGPT: Compressing LLMs with Structured Matrices and Orthogonal Transformations. In Findings of the Association for Computational Linguistics: ACL 2025, pages 26937–26949, Vienna, Austria. Association for Computational Linguistics.
Cite (Informal):
ProcrustesGPT: Compressing LLMs with Structured Matrices and Orthogonal Transformations (Grishina et al., Findings 2025)
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https://preview.aclanthology.org/display_plenaries/2025.findings-acl.1381.pdf