Document Alignment based on Overlapping Fixed-Length Segments

Acquiring large-scale parallel corpora is crucial for NLP tasks such as Neural Machine Translation, and web crawling has become a popular methodology for this purpose. Previous studies have been conducted based on sentencebased segmentation (SBS) when aligning documents in various languages which are obtained through web crawling. Among them, the TK-PERT method (Thompson and Koehn, 2020) achieved state-of-the-art results and addressed the boilerplate text in web crawling data well through a down-weighting approach. However, there remains a problem with how to handle long-text encoding better. Thus, we introduce the strategy of Overlapping Fixed-Length Segmentation (OFLS) in place of SBS, and observe a pronounced enhancement when performing the same approach for document alignment. In this paper, we compare the SBS and OFLS using three previous methods, Mean-Pool, TK-PERT (Thompson and Koehn, 2020), and Optimal Transport (Clark et al., 2019; El-Kishky and Guzmán, 2020) , on the WMT16 document alignment shared task for French-English, as well as on our self-established Japanese-English dataset MnRN. As a result, for the WMT16 task, various SBS based methods showed an increase in recall by 1% to 10% after reproduction with OFLS. For MnRN data, OFLS demonstrated notable accuracy improvements and exhibited faster document embedding speed.