Word ordering remains as an essential problem for translating between languages with substantial structural differences, such as SOV and SVO languages. In this paper, we propose to automatically extract pre-ordering rules from predicateargument structures. A pre-ordering rule records the relative position mapping of a predicate word and its argument phrases from the source language side to the target language side. We propose 1) a lineartime algorithm to extract the pre-ordering rules from word-aligned HPSG-tree-tostring pairs and 2) a bottom-up algorithm to apply the extracted rules to HPSG trees to yield target language style source sentences. Experimental results are reported for large-scale English-to-Japanese translation, showing significant improvements of BLEU score compared with the baseline SMT systems.
In the pre-ordering approach, REF automatically learned pre-ordering rules from PAS.
Extracting Pre-ordering Rules from Predicate-Argument Structures
IJCNLP
Computer Science