Although it is appealing to apply our approach to dealing with real-world non-parallel corpora, it is time-consuming and labor-intensive to manually construct a ground truth parallel corpus.
they introduce a corpus-level latentvariable translation model in a non-parallel scenario and develop a training algorithm that alternates between (1) using a parallel lexicon to extract parallel phrases from non-parallel corpora and (2) using the extracted parallel phrases to enlarge the parallel lexicon.