A Fast And Accurate Method For Detecting English-Japanese Parallel Texts

Parallel corpus is a valuable resource used in various fields of multilingual natural language processing. One of the most significant problems in using parallel corpora is the lack of their availability. Researchers have investigated approaches to collecting parallel texts from the Web. A basic component of these approaches is an algorithm that judges whether a pair of texts is parallel or not. In this paper, we propose an algorithm that accelerates this task without losing accuracy by preprocessing a bilingual dictionary as well as the collection of texts. This method achieved 250,000 pairs/sec throughput on a single CPU, with the best F1 score of 0.960 for the task of detecting 200 Japanese-English translation pairs out of 40, 000. The method is applicable to texts of any format, and not specific to HTML documents labeled with URLs. We report details of these preprocessing methods and the fast comparison algorithm. To the best of our knowledge, this is the first reported experiment of extracting Japanese– English parallel texts from a large corpora based solely on linguistic content.