Length Extrapolation of Transformers: A Survey from the Perspective of Positional Encoding

Fuente: arXiv
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Autores principales: Zhao, Liang, Feng, Xiachong, Feng, Xiaocheng, Zhong, Weihong, Xu, Dongliang, Yang, Qing, Liu, Hongtao, Qin, Bing, Liu, Ting
Formato: Preprint
Publicado: 2023
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author Zhao, Liang
Feng, Xiachong
Feng, Xiaocheng
Zhong, Weihong
Xu, Dongliang
Yang, Qing
Liu, Hongtao
Qin, Bing
Liu, Ting
author_facet Zhao, Liang
Feng, Xiachong
Feng, Xiaocheng
Zhong, Weihong
Xu, Dongliang
Yang, Qing
Liu, Hongtao
Qin, Bing
Liu, Ting
contents Built upon the Transformer, large language models (LLMs) have captured worldwide attention due to their remarkable abilities. Nevertheless, all Transformer-based models including LLMs suffer from a preset length limit and can hardly generalize from short training sequences to longer inference ones, namely, they cannot perform length extrapolation to handle long sequences, which severely hinders their application in scenarios demanding long input sequences such as legal or scientific documents. Thus, numerous methods have emerged to enhance the length extrapolation of Transformers. Despite the great research efforts, a systematic survey is still lacking. To fill this gap, we delve into these advances in a unified notation from the perspective of positional encoding (PE), as it has been considered the primary factor on length extrapolation. Specifically, we begin with extrapolatable PEs that have dominated this research field. Then, we dive into extrapolation methods based on them, covering position interpolation and randomized position methods. Finally, several challenges and future directions in this area are highlighted. Through this survey, we aim to enable the reader to gain a deep understanding of existing methods and provide stimuli for future research.
format Preprint
id arxiv_https___arxiv_org_abs_2312_17044
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle Length Extrapolation of Transformers: A Survey from the Perspective of Positional Encoding
Zhao, Liang
Feng, Xiachong
Feng, Xiaocheng
Zhong, Weihong
Xu, Dongliang
Yang, Qing
Liu, Hongtao
Qin, Bing
Liu, Ting
Computation and Language
Built upon the Transformer, large language models (LLMs) have captured worldwide attention due to their remarkable abilities. Nevertheless, all Transformer-based models including LLMs suffer from a preset length limit and can hardly generalize from short training sequences to longer inference ones, namely, they cannot perform length extrapolation to handle long sequences, which severely hinders their application in scenarios demanding long input sequences such as legal or scientific documents. Thus, numerous methods have emerged to enhance the length extrapolation of Transformers. Despite the great research efforts, a systematic survey is still lacking. To fill this gap, we delve into these advances in a unified notation from the perspective of positional encoding (PE), as it has been considered the primary factor on length extrapolation. Specifically, we begin with extrapolatable PEs that have dominated this research field. Then, we dive into extrapolation methods based on them, covering position interpolation and randomized position methods. Finally, several challenges and future directions in this area are highlighted. Through this survey, we aim to enable the reader to gain a deep understanding of existing methods and provide stimuli for future research.
title Length Extrapolation of Transformers: A Survey from the Perspective of Positional Encoding
topic Computation and Language
url https://arxiv.org/abs/2312.17044