Kosuke Takahashi
2020
Automatic Machine Translation Evaluation using Source Language Inputs and Cross-lingual Language Model
Kosuke Takahashi
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Katsuhito Sudoh
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Satoshi Nakamura
Proceedings of the 58th Annual Meeting of the Association for Computational Linguistics
We propose an automatic evaluation method of machine translation that uses source language sentences regarded as additional pseudo references. The proposed method evaluates a translation hypothesis in a regression model. The model takes the paired source, reference, and hypothesis sentence all together as an input. A pretrained large scale cross-lingual language model encodes the input to sentence-pair vectors, and the model predicts a human evaluation score with those vectors. Our experiments show that our proposed method using Cross-lingual Language Model (XLM) trained with a translation language modeling (TLM) objective achieves a higher correlation with human judgments than a baseline method that uses only hypothesis and reference sentences. Additionally, using source sentences in our proposed method is confirmed to improve the evaluation performance.