Delay Embedding Theory of Neural Sequence Models

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Hauptverfasser: Ostrow, Mitchell, Eisen, Adam, Fiete, Ila
Format: Preprint
Veröffentlicht: 2024
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author Ostrow, Mitchell
Eisen, Adam
Fiete, Ila
author_facet Ostrow, Mitchell
Eisen, Adam
Fiete, Ila
contents To generate coherent responses, language models infer unobserved meaning from their input text sequence. One potential explanation for this capability arises from theories of delay embeddings in dynamical systems, which prove that unobserved variables can be recovered from the history of only a handful of observed variables. To test whether language models are effectively constructing delay embeddings, we measure the capacities of sequence models to reconstruct unobserved dynamics. We trained 1-layer transformer decoders and state-space sequence models on next-step prediction from noisy, partially-observed time series data. We found that each sequence layer can learn a viable embedding of the underlying system. However, state-space models have a stronger inductive bias than transformers-in particular, they more effectively reconstruct unobserved information at initialization, leading to more parameter-efficient models and lower error on dynamics tasks. Our work thus forges a novel connection between dynamical systems and deep learning sequence models via delay embedding theory.
format Preprint
id arxiv_https___arxiv_org_abs_2406_11993
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Delay Embedding Theory of Neural Sequence Models
Ostrow, Mitchell
Eisen, Adam
Fiete, Ila
Machine Learning
Neural and Evolutionary Computing
To generate coherent responses, language models infer unobserved meaning from their input text sequence. One potential explanation for this capability arises from theories of delay embeddings in dynamical systems, which prove that unobserved variables can be recovered from the history of only a handful of observed variables. To test whether language models are effectively constructing delay embeddings, we measure the capacities of sequence models to reconstruct unobserved dynamics. We trained 1-layer transformer decoders and state-space sequence models on next-step prediction from noisy, partially-observed time series data. We found that each sequence layer can learn a viable embedding of the underlying system. However, state-space models have a stronger inductive bias than transformers-in particular, they more effectively reconstruct unobserved information at initialization, leading to more parameter-efficient models and lower error on dynamics tasks. Our work thus forges a novel connection between dynamical systems and deep learning sequence models via delay embedding theory.
title Delay Embedding Theory of Neural Sequence Models
topic Machine Learning
Neural and Evolutionary Computing
url https://arxiv.org/abs/2406.11993