Don't Rank, Combine! Combining Machine Translation Hypotheses Using Quality Estimation

Fuente: arXiv
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Main Authors: Vernikos, Giorgos, Popescu-Belis, Andrei
Format: Preprint
Published: 2024
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author Vernikos, Giorgos
Popescu-Belis, Andrei
author_facet Vernikos, Giorgos
Popescu-Belis, Andrei
contents Neural machine translation systems estimate probabilities of target sentences given source sentences, yet these estimates may not align with human preferences. This work introduces QE-fusion, a method that synthesizes translations using a quality estimation metric (QE), which correlates better with human judgments. QE-fusion leverages a pool of candidates sampled from a model, combining spans from different candidates using a QE metric such as CometKiwi. We compare QE-fusion against beam search and recent reranking techniques, such as Minimum Bayes Risk decoding or QE-reranking. Our method consistently improves translation quality in terms of COMET and BLEURT scores when applied to large language models (LLMs) used for translation (PolyLM, XGLM, Llama2, Mistral, ALMA, and Tower) and to multilingual translation models (NLLB), over five language pairs. Notably, QE-fusion exhibits larger improvements for LLMs due to their ability to generate diverse outputs. We demonstrate that our approach generates novel translations in over half of the cases and consistently outperforms other methods across varying numbers of candidates (5-200). Furthermore, we empirically establish that QE-fusion scales linearly with the number of candidates in the pool.
format Preprint
id arxiv_https___arxiv_org_abs_2401_06688
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Don't Rank, Combine! Combining Machine Translation Hypotheses Using Quality Estimation
Vernikos, Giorgos
Popescu-Belis, Andrei
Computation and Language
Machine Learning
Neural machine translation systems estimate probabilities of target sentences given source sentences, yet these estimates may not align with human preferences. This work introduces QE-fusion, a method that synthesizes translations using a quality estimation metric (QE), which correlates better with human judgments. QE-fusion leverages a pool of candidates sampled from a model, combining spans from different candidates using a QE metric such as CometKiwi. We compare QE-fusion against beam search and recent reranking techniques, such as Minimum Bayes Risk decoding or QE-reranking. Our method consistently improves translation quality in terms of COMET and BLEURT scores when applied to large language models (LLMs) used for translation (PolyLM, XGLM, Llama2, Mistral, ALMA, and Tower) and to multilingual translation models (NLLB), over five language pairs. Notably, QE-fusion exhibits larger improvements for LLMs due to their ability to generate diverse outputs. We demonstrate that our approach generates novel translations in over half of the cases and consistently outperforms other methods across varying numbers of candidates (5-200). Furthermore, we empirically establish that QE-fusion scales linearly with the number of candidates in the pool.
title Don't Rank, Combine! Combining Machine Translation Hypotheses Using Quality Estimation
topic Computation and Language
Machine Learning
url https://arxiv.org/abs/2401.06688