... one -to- one relations but not one -to- many, many -to- one, many -to- many or null relations, all of which can occur in word alignments. We constrain the forbidden types of relation to become one -to- one, ... 2011). Thus, in a one -to- many alignment, the single source word is forced to align with the first target word; in a many -to- one alignment, monotone order is assumed for the target words; ... scores. To be fair to both metrics, for each condition, we took the union of examples whose BLEU-tuned output was in the top n% of BLEU outputs and those whose PORT-tuned output was in the top...