Synthetic Method: It aims to create a synthetic source-target corpus by: (1) translate the pivot part in source-pivot corpus into target language with a pivot-target model; (2) translate the pivot part in pivot-target corpus into source language with a pivot-source model; (3) combine the source sentences with translated target sentences or/and combine the target sentences with translated source sentences (Utiyama et al., 2008;Wu and Wang, 2009).
it is difficult to build a high quality translation system with a corpus created by a machine translation system.