Case frame constraints for hierarchical phrase-based translation: Japanese-chinese as an example

Abstract

Hierarchical phrase-based model has two main problems. Firstly, without any semantic guidance, large numbers of redundant rules are extracted. Secondly, it cannot efficiently capture long reordering. This paper proposes a novel approach to exploiting case frame in hierarchical phrase-based model in both rule extraction and decoding. Case frame is developed by case grammar theory, and it captures sentence structure and assigns components with different case information. Our case frame constraints system holds the properties of long distance reordering and phrase in case chunk-based dependency tree. At the same time, the number of HPB rules decrease with the case frame constraints. The results of experiments carried out on Japanese-Chinese test sets shows that our approach yields improvements over the HPB model (+1.48 BLEU on average).