Fast Decoding and Optimal Decoding for Machine Translation

July 18, 2001

**Winner of the ACL 2001 Best Paper Award**

A good decoding algorithm is critical to the success of any statistical machine translation system. The decoder's job is to find the translation that is most likely according to set of previously learned parameters. Since the space of possible translations is extremely large, typical decoding algorithms are only able to examine a portion of it, thus risking missing good solutions. In this paper, we compare the speed and output quality of a traditional stack-based decoding algorithm with two new decoders: a fast greedy decoder and a slow but optimal decoder that treats decoding as an integer-programming optimization problem.