基于局部优先和嵌套层次的二元组合语法分析模型

Binary Combinatorial Grammar Parsing Model Based on Local Priority and Nesting Level

依存语法中由于缺乏对句法功能结构的描述机制,不能显性表达某些复杂的句法结构.修饰词的嵌套层次虽是语用学的常识,却极少有语法分析模型考虑该信息.针对这两个问题,文中提出一种融合嵌套层次的生成性二元组合语法分析模型.该模型将句子的构成看作按中心词进行的相邻语块的两两组合,应用组合关系之间的优先级和嵌套层次来约束句法树的生成.通过转换依存树库得到二元组合语法树库,然后基于该树库自动获取语法关系、优先级信息和模型参数,构建二元组合语法分析模型.实验结果表明该模型能有效提高句法分析的正确率.

Due to the lack of descriptive mechanism for syntactic functional structure, the dependency grammar can not express all complex syntactic structures explicitly. In addition, few parsing model takes the restrictive information of modifiers＂ nesting level into account, though it is a common sense in pragmatics. To solve these problems, a generative binary combinational grammar （BCG） parsing model is proposed which incorporates the restrictive information. In this model, the construction of sentence is regarded as the combination of adjacent chunks according to their headwords. Moreover, the symbolic local priorities between the adjacent binary relations and the modifiers＂ nesting levels are used to constrain the generation of parsing trees. The BCG parsing model is constructed by converting the dependency treebank to the BCG form. Then, the syntactic relations, the local priorities and the parameters of the model are induced automatically. Experimental results show that the proposed model improves the parsing accuracy.