Extracting Paraphrases from a Parallel Corpus 
 While paraphrasing is critical both for interpretation and generation of natural language , current systems use manual or semi-automatic methods to collect paraphrases . We present an unsupervised learning algorithm for identification of paraphrases from a corpus of multiple English translations of the same source text . Our approach yields phrasal and single word lexical paraphrases as well as syntactic paraphrases . 