Understanding and Addressing the Under-Translation Problem from the Perspective of Decoding Objective

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Main Authors: Shao, Chenze, Meng, Fandong, Zeng, Jiali, Zhou, Jie
Format: Preprint
Published: 2024
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author Shao, Chenze
Meng, Fandong
Zeng, Jiali
Zhou, Jie
author_facet Shao, Chenze
Meng, Fandong
Zeng, Jiali
Zhou, Jie
contents Neural Machine Translation (NMT) has made remarkable progress over the past years. However, under-translation and over-translation remain two challenging problems in state-of-the-art NMT systems. In this work, we conduct an in-depth analysis on the underlying cause of under-translation in NMT, providing an explanation from the perspective of decoding objective. To optimize the beam search objective, the model tends to overlook words it is less confident about, leading to the under-translation phenomenon. Correspondingly, the model's confidence in predicting the End Of Sentence (EOS) diminishes when under-translation occurs, serving as a mild penalty for under-translated candidates. Building upon this analysis, we propose employing the confidence of predicting EOS as a detector for under-translation, and strengthening the confidence-based penalty to penalize candidates with a high risk of under-translation. Experiments on both synthetic and real-world data show that our method can accurately detect and rectify under-translated outputs, with minor impact on other correct translations.
format Preprint
id arxiv_https___arxiv_org_abs_2405_18922
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Understanding and Addressing the Under-Translation Problem from the Perspective of Decoding Objective
Shao, Chenze
Meng, Fandong
Zeng, Jiali
Zhou, Jie
Computation and Language
Neural Machine Translation (NMT) has made remarkable progress over the past years. However, under-translation and over-translation remain two challenging problems in state-of-the-art NMT systems. In this work, we conduct an in-depth analysis on the underlying cause of under-translation in NMT, providing an explanation from the perspective of decoding objective. To optimize the beam search objective, the model tends to overlook words it is less confident about, leading to the under-translation phenomenon. Correspondingly, the model's confidence in predicting the End Of Sentence (EOS) diminishes when under-translation occurs, serving as a mild penalty for under-translated candidates. Building upon this analysis, we propose employing the confidence of predicting EOS as a detector for under-translation, and strengthening the confidence-based penalty to penalize candidates with a high risk of under-translation. Experiments on both synthetic and real-world data show that our method can accurately detect and rectify under-translated outputs, with minor impact on other correct translations.
title Understanding and Addressing the Under-Translation Problem from the Perspective of Decoding Objective
topic Computation and Language
url https://arxiv.org/abs/2405.18922