中心词驱动的短语结构句法分析器。该模型考虑了跟随介词短语的名词短语的中心词的作用。 有MIT大学Colling开发，是目前国际上工人的最好的英语句法分析器-Head-driven Phrase Structure Parser. The model considered the prepositional phrase following the noun phrase the central role of the word. MIT has developed the Universit

impmemt doubly linkked list, includes head, tail, addafter etc funciton