Nuno Guerreiro
2023
Steering Large Language Models for Machine Translation with Finetuning and In-Context Learning
Duarte Alves
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Nuno Guerreiro
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João Alves
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José Pombal
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Ricardo Rei
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José de Souza
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Pierre Colombo
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Andre Martins
Findings of the Association for Computational Linguistics: EMNLP 2023
Large language models (LLMs) are a promising avenue for machine translation (MT). However, current LLM-based MT systems are brittle: their effectiveness highly depends on the choice of few-shot examples and they often require extra post-processing due to overgeneration. Alternatives such as finetuning on translation instructions are computationally expensive and may weaken in-context learning capabilities, due to overspecialization. In this paper, we provide a closer look at this problem. We start by showing that adapter-based finetuning with LoRA matches the performance of traditional finetuning while reducing the number of training parameters by a factor of 50. This method also outperforms few-shot prompting and eliminates the need for post-processing or in-context examples. However, we show that finetuning generally degrades few-shot performance, hindering adaptation capabilities. Finally, to obtain the best of both worlds, we propose a simple approach that incorporates few-shot examples during finetuning. Experiments on 10 language pairs show that our proposed approach recovers the original few-shot capabilities while keeping the added benefits of finetuning.
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Co-authors
- Duarte Alves 1
- João Alves 1
- José Pombal 1
- Ricardo Rei 1
- José de Souza 1
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