Compute Optimal Inference and Provable Amortisation Gap in Sparse Autoencoders

Fuente: arXiv
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Main Authors: O'Neill, Charles, Gumran, Alim, Klindt, David
Format: Preprint
Published: 2024
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author O'Neill, Charles
Gumran, Alim
Klindt, David
author_facet O'Neill, Charles
Gumran, Alim
Klindt, David
contents A recent line of work has shown promise in using sparse autoencoders (SAEs) to uncover interpretable features in neural network representations. However, the simple linear-nonlinear encoding mechanism in SAEs limits their ability to perform accurate sparse inference. Using compressed sensing theory, we prove that an SAE encoder is inherently insufficient for accurate sparse inference, even in solvable cases. We then decouple encoding and decoding processes to empirically explore conditions where more sophisticated sparse inference methods outperform traditional SAE encoders. Our results reveal substantial performance gains with minimal compute increases in correct inference of sparse codes. We demonstrate this generalises to SAEs applied to large language models, where more expressive encoders achieve greater interpretability. This work opens new avenues for understanding neural network representations and analysing large language model activations.
format Preprint
id arxiv_https___arxiv_org_abs_2411_13117
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Compute Optimal Inference and Provable Amortisation Gap in Sparse Autoencoders
O'Neill, Charles
Gumran, Alim
Klindt, David
Machine Learning
A recent line of work has shown promise in using sparse autoencoders (SAEs) to uncover interpretable features in neural network representations. However, the simple linear-nonlinear encoding mechanism in SAEs limits their ability to perform accurate sparse inference. Using compressed sensing theory, we prove that an SAE encoder is inherently insufficient for accurate sparse inference, even in solvable cases. We then decouple encoding and decoding processes to empirically explore conditions where more sophisticated sparse inference methods outperform traditional SAE encoders. Our results reveal substantial performance gains with minimal compute increases in correct inference of sparse codes. We demonstrate this generalises to SAEs applied to large language models, where more expressive encoders achieve greater interpretability. This work opens new avenues for understanding neural network representations and analysing large language model activations.
title Compute Optimal Inference and Provable Amortisation Gap in Sparse Autoencoders
topic Machine Learning
url https://arxiv.org/abs/2411.13117