Adapters for Altering LLM Vocabularies: What Languages Benefit the Most?

Fuente: arXiv
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Autores principales: Han, HyoJung, Eriguchi, Akiko, Xu, Haoran, Hoang, Hieu, Carpuat, Marine, Khayrallah, Huda
Formato: Preprint
Publicado: 2024
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author Han, HyoJung
Eriguchi, Akiko
Xu, Haoran
Hoang, Hieu
Carpuat, Marine
Khayrallah, Huda
author_facet Han, HyoJung
Eriguchi, Akiko
Xu, Haoran
Hoang, Hieu
Carpuat, Marine
Khayrallah, Huda
contents Vocabulary adaptation, which integrates new vocabulary into pre-trained language models, enables expansion to new languages and mitigates token over-fragmentation. However, existing approaches are limited by their reliance on heuristics or external embeddings. We propose VocADT, a novel method for vocabulary adaptation using adapter modules that are trained to learn the optimal linear combination of existing embeddings while keeping the model's weights fixed. VocADT offers a flexible and scalable solution without depending on external resources or language constraints. Across 11 languages-with diverse scripts, resource availability, and fragmentation-we demonstrate that VocADT outperforms the original Mistral model and other baselines across various multilingual tasks including natural language understanding and machine translation. We find that Latin-script languages and highly fragmented languages benefit the most from vocabulary adaptation. We further fine-tune the adapted model on the generative task of machine translation and find that vocabulary adaptation is still beneficial after fine-tuning and that VocADT is the most effective.
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publishDate 2024
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spellingShingle Adapters for Altering LLM Vocabularies: What Languages Benefit the Most?
Han, HyoJung
Eriguchi, Akiko
Xu, Haoran
Hoang, Hieu
Carpuat, Marine
Khayrallah, Huda
Computation and Language
Vocabulary adaptation, which integrates new vocabulary into pre-trained language models, enables expansion to new languages and mitigates token over-fragmentation. However, existing approaches are limited by their reliance on heuristics or external embeddings. We propose VocADT, a novel method for vocabulary adaptation using adapter modules that are trained to learn the optimal linear combination of existing embeddings while keeping the model's weights fixed. VocADT offers a flexible and scalable solution without depending on external resources or language constraints. Across 11 languages-with diverse scripts, resource availability, and fragmentation-we demonstrate that VocADT outperforms the original Mistral model and other baselines across various multilingual tasks including natural language understanding and machine translation. We find that Latin-script languages and highly fragmented languages benefit the most from vocabulary adaptation. We further fine-tune the adapted model on the generative task of machine translation and find that vocabulary adaptation is still beneficial after fine-tuning and that VocADT is the most effective.
title Adapters for Altering LLM Vocabularies: What Languages Benefit the Most?
topic Computation and Language
url https://arxiv.org/abs/2410.09644