SeqPO-SiMT: Sequential Policy Optimization for Simultaneous Machine Translation

Fuente: arXiv
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Main Authors: Xu, Ting, Huang, Zhichao, Sun, Jiankai, Cheng, Shanbo, Lam, Wai
Format: Preprint
Published: 2025
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author Xu, Ting
Huang, Zhichao
Sun, Jiankai
Cheng, Shanbo
Lam, Wai
author_facet Xu, Ting
Huang, Zhichao
Sun, Jiankai
Cheng, Shanbo
Lam, Wai
contents We present Sequential Policy Optimization for Simultaneous Machine Translation (SeqPO-SiMT), a new policy optimization framework that defines the simultaneous machine translation (SiMT) task as a sequential decision making problem, incorporating a tailored reward to enhance translation quality while reducing latency. In contrast to popular Reinforcement Learning from Human Feedback (RLHF) methods, such as PPO and DPO, which are typically applied in single-step tasks, SeqPO-SiMT effectively tackles the multi-step SiMT task. This intuitive framework allows the SiMT LLMs to simulate and refine the SiMT process using a tailored reward. We conduct experiments on six datasets from diverse domains for En to Zh and Zh to En SiMT tasks, demonstrating that SeqPO-SiMT consistently achieves significantly higher translation quality with lower latency. In particular, SeqPO-SiMT outperforms the supervised fine-tuning (SFT) model by 1.13 points in COMET, while reducing the Average Lagging by 6.17 in the NEWSTEST2021 En to Zh dataset. While SiMT operates with far less context than offline translation, the SiMT results of SeqPO-SiMT on 7B LLM surprisingly rival the offline translation of high-performing LLMs, including Qwen-2.5-7B-Instruct and LLaMA-3-8B-Instruct.
format Preprint
id arxiv_https___arxiv_org_abs_2505_20622
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle SeqPO-SiMT: Sequential Policy Optimization for Simultaneous Machine Translation
Xu, Ting
Huang, Zhichao
Sun, Jiankai
Cheng, Shanbo
Lam, Wai
Computation and Language
Artificial Intelligence
Machine Learning
We present Sequential Policy Optimization for Simultaneous Machine Translation (SeqPO-SiMT), a new policy optimization framework that defines the simultaneous machine translation (SiMT) task as a sequential decision making problem, incorporating a tailored reward to enhance translation quality while reducing latency. In contrast to popular Reinforcement Learning from Human Feedback (RLHF) methods, such as PPO and DPO, which are typically applied in single-step tasks, SeqPO-SiMT effectively tackles the multi-step SiMT task. This intuitive framework allows the SiMT LLMs to simulate and refine the SiMT process using a tailored reward. We conduct experiments on six datasets from diverse domains for En to Zh and Zh to En SiMT tasks, demonstrating that SeqPO-SiMT consistently achieves significantly higher translation quality with lower latency. In particular, SeqPO-SiMT outperforms the supervised fine-tuning (SFT) model by 1.13 points in COMET, while reducing the Average Lagging by 6.17 in the NEWSTEST2021 En to Zh dataset. While SiMT operates with far less context than offline translation, the SiMT results of SeqPO-SiMT on 7B LLM surprisingly rival the offline translation of high-performing LLMs, including Qwen-2.5-7B-Instruct and LLaMA-3-8B-Instruct.
title SeqPO-SiMT: Sequential Policy Optimization for Simultaneous Machine Translation
topic Computation and Language
Artificial Intelligence
Machine Learning
url https://arxiv.org/abs/2505.20622