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Towards Universality: Studying Mechanistic Similarity Across Language Model Architectures

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arxiv 2410.06672 v2 pith:ZLM2KLWH submitted 2024-10-09 cs.CL

Towards Universality: Studying Mechanistic Similarity Across Language Model Architectures

classification cs.CL
keywords modelssimilarsimilaritytransformersuniversalityarchitecturesfeatureslanguage
verification ladder T0 review T1 audit T2 compute T3 formal T4 reserved
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The hypothesis of Universality in interpretability suggests that different neural networks may converge to implement similar algorithms on similar tasks. In this work, we investigate two mainstream architectures for language modeling, namely Transformers and Mambas, to explore the extent of their mechanistic similarity. We propose to use Sparse Autoencoders (SAEs) to isolate interpretable features from these models and show that most features are similar in these two models. We also validate the correlation between feature similarity and Universality. We then delve into the circuit-level analysis of Mamba models and find that the induction circuits in Mamba are structurally analogous to those in Transformers. We also identify a nuanced difference we call \emph{Off-by-One motif}: The information of one token is written into the SSM state in its next position. Whilst interaction between tokens in Transformers does not exhibit such trend.

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Cited by 6 Pith papers

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