【摘要】 树库是一种带句法标注的语料库,它记录着真实文本中每个句子的句法分析结果——句法树。上世纪90年代,自然语言的自动句法分析再次成为国际计算语言学界关注的焦点,一个重要原因是美国宾州树库PTB的建成。根据树库自动归纳出来的概率型上下文无关语法,使英语的句法分析器在性能上显著超越了先前基于规则和合一运算的句法分析器。世界上为各种自然语言构建的树库,不论是短语结构树库还是依存结构树库,都以句子为基本的描述单位。依存语法是一种词例化语法,它不采用短语结构的语法概念,而直接描写句子中词与词之间的依存关系,即认为句子中任何两个具有依存关系的词中必有一个是中心词(支配词),而另一个是被支配词。因此,依存语法直接体现了一种语言的句法层面和语义层面之间的天然联系。这充分说明,黎锦熙先生在《新著国语文法》中倡导的句本位语法体系和中心词分析法具有鲜活的生命力。它们不仅在我国解放前后的中学语文教学中数十年长盛不衰,而且至今仍在指导着树库的建设和应用。更多还原

【Abstract】 Treebank is a text corpus with syntactic annotation. It records the syntactic tree, i.e. the syntactic parse, of every sentence in running texts. Since 1990s, automatic parsing of natural languages has again become the focus of the international community of computational linguistics, and one of the crucial reasons is the realization of the Penn Treebank (PTB). The performances of statistical parsers, which are based on automatically induced Probabilistic Context-Free Grammar (PCFG), outperform significantly those rule-and unification-based parsers. A Treebank of any language in the world, represented with either phrase structures or dependency structures, takes sentence as its basic description unit. Dependency Grammar is a lexicalized grammar; it denies the notion of phrase structures and describes only the various word-word relations in a sentence, in which the head-word is the dominant of a given relation, and the other word of the word-pair at stake is the dependent of the head. Dependency Grammar creates a transparent interface between the dependency syntax and semantics of a language. This paper highly estimates the life force of the sentence-based syntax and the head-driven sentence analyzing method advocated by Jinxi Li, because they have not only dominated grammar teaching in middle schools more than half century before and after the foundation of the People’s Republic of China, but also guides the treebanking practice today.更多还原