Our key insight is that target transformations can be detected (with some noise) simply by parsing these pairs.
3 we parse the backtranslated paraphrases using the Stanford parser , 4 which yields a pair of constituency parses p 1 , p 2 for each sentence pair s 1 , s 2 , where s 1 is the reference English sentence in the CzEng corpus and s 2 is its backtranslated counterpart.