A hierarchy-based constraint dependency grammar parsing for Chinese

Constraint Dependency Grammar (CDG) is a well known formalism which represents the grammatical rules as constraints on dependency relations. It reduces the structural ambiguities via constraint-propagation instead of generating individual parse trees as the conventional works. In our previous work, we have successfully adopted CDG in Chinese [5]. In this paper, we tend to further explore the nature of the constraints for Chinese CDG. We propose to develop a schema of three hierarchies for the constraints, namely in-the-phrase, between-the-phrase and between-the-simple-sentence, which is based on a study of constraints in corpus with a prior knowledge. With this proposed schema, we could further diminish the ambiguities caused by the originally defined constraints which is lack of hierarchical grammar information considered, The experiments are conducted and the results support our claims.