ToPro: Token-Level Prompt Decomposition for Cross-Lingual Sequence Labeling Tasks

Bolei Ma, Ercong Nie, Shuzhou Yuan, Helmut Schmid, Michael Färber, Frauke Kreuter, Hinrich Schuetze


Abstract
Prompt-based methods have been successfully applied to multilingual pretrained language models for zero-shot cross-lingual understanding. However, most previous studies primarily focused on sentence-level classification tasks, and only a few considered token-level labeling tasks such as Named Entity Recognition (NER) and Part-of-Speech (POS) tagging. In this paper, we propose Token-Level Prompt Decomposition (ToPro), which facilitates the prompt-based method for token-level sequence labeling tasks. The ToPro method decomposes an input sentence into single tokens and applies one prompt template to each token. Our experiments on multilingual NER and POS tagging datasets demonstrate that ToPro-based fine-tuning outperforms Vanilla fine-tuning and Prompt-Tuning in zero-shot cross-lingual transfer, especially for languages that are typologically different from the source language English. Our method also attains state-of-the-art performance when employed with the mT5 model. Besides, our exploratory study in multilingual large language models shows that ToPro performs much better than the current in-context learning method. Overall, the performance improvements show that ToPro could potentially serve as a novel and simple benchmarking method for sequence labeling tasks.
Anthology ID:
2024.eacl-long.164
Original:
2024.eacl-long.164v1
Version 2:
2024.eacl-long.164v2
Volume:
Proceedings of the 18th Conference of the European Chapter of the Association for Computational Linguistics (Volume 1: Long Papers)
Month:
March
Year:
2024
Address:
St. Julian’s, Malta
Editors:
Yvette Graham, Matthew Purver
Venue:
EACL
SIG:
Publisher:
Association for Computational Linguistics
Note:
Pages:
2685–2702
Language:
URL:
https://aclanthology.org/2024.eacl-long.164
DOI:
Bibkey:
Cite (ACL):
Bolei Ma, Ercong Nie, Shuzhou Yuan, Helmut Schmid, Michael Färber, Frauke Kreuter, and Hinrich Schuetze. 2024. ToPro: Token-Level Prompt Decomposition for Cross-Lingual Sequence Labeling Tasks. In Proceedings of the 18th Conference of the European Chapter of the Association for Computational Linguistics (Volume 1: Long Papers), pages 2685–2702, St. Julian’s, Malta. Association for Computational Linguistics.
Cite (Informal):
ToPro: Token-Level Prompt Decomposition for Cross-Lingual Sequence Labeling Tasks (Ma et al., EACL 2024)
Copy Citation:
PDF:
https://aclanthology.org/2024.eacl-long.164.pdf
Video:
 https://aclanthology.org/2024.eacl-long.164.mp4