nltk/nltk — pull request #724 by alvations (2014-08-05 20:19:03+00:00)
Title: Added Phrase Extraction Algorithm for Phrase-based MT in nltk.align

Added the phrase extraction algorithm from Philip Koehn (2009) Statistical Machine Translation book.
Phrase extraction algorithm found on page 133. Also note that the original book has an error in the algorithm, see errata http://www.statmt.org/book/errata.html.