Transformers Provably Learn Sparse Token Selection While Fully-Connected Nets Cannot

Fuente: arXiv
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Main Authors: Wang, Zixuan, Wei, Stanley, Hsu, Daniel, Lee, Jason D.
Format: Preprint
Published: 2024
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author Wang, Zixuan
Wei, Stanley
Hsu, Daniel
Lee, Jason D.
author_facet Wang, Zixuan
Wei, Stanley
Hsu, Daniel
Lee, Jason D.
contents The transformer architecture has prevailed in various deep learning settings due to its exceptional capabilities to select and compose structural information. Motivated by these capabilities, Sanford et al. proposed the sparse token selection task, in which transformers excel while fully-connected networks (FCNs) fail in the worst case. Building upon that, we strengthen the FCN lower bound to an average-case setting and establish an algorithmic separation of transformers over FCNs. Specifically, a one-layer transformer trained with gradient descent provably learns the sparse token selection task and, surprisingly, exhibits strong out-of-distribution length generalization. We provide empirical simulations to justify our theoretical findings.
format Preprint
id arxiv_https___arxiv_org_abs_2406_06893
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Transformers Provably Learn Sparse Token Selection While Fully-Connected Nets Cannot
Wang, Zixuan
Wei, Stanley
Hsu, Daniel
Lee, Jason D.
Machine Learning
Information Theory
The transformer architecture has prevailed in various deep learning settings due to its exceptional capabilities to select and compose structural information. Motivated by these capabilities, Sanford et al. proposed the sparse token selection task, in which transformers excel while fully-connected networks (FCNs) fail in the worst case. Building upon that, we strengthen the FCN lower bound to an average-case setting and establish an algorithmic separation of transformers over FCNs. Specifically, a one-layer transformer trained with gradient descent provably learns the sparse token selection task and, surprisingly, exhibits strong out-of-distribution length generalization. We provide empirical simulations to justify our theoretical findings.
title Transformers Provably Learn Sparse Token Selection While Fully-Connected Nets Cannot
topic Machine Learning
Information Theory
url https://arxiv.org/abs/2406.06893