tailieunhanh - Báo cáo khoa học: "A Statistical Tree Annotator and Its Applications"

In many natural language applications, there is a need to enrich syntactical parse trees. We present a statistical tree annotator augmenting nodes with additional information. The annotator is generic and can be applied to a variety of applications. We report 3 such applications in this paper: predicting function tags; predicting null elements; and predicting whether a tree constituent is projectable in machine translation. Our function tag prediction system outperforms significantly published results. . | A Statistical Tree Annotator and Its Applications Xiaoqiang Luo and Bing Zhao IBM . Watson Research Center 1101 Kitchawan Road Yorktown Heights NY 10598 xiaoluo zhaob @ Abstract In many natural language applications there is a need to enrich syntactical parse trees. We present a statistical tree annotator augmenting nodes with additional information. The annotator is generic and can be applied to a variety of applications. We report 3 such applications in this paper predicting function tags predicting null elements and predicting whether a tree constituent is projectable in machine translation. Our function tag prediction system outperforms significantly published results. 1 Introduction Syntactic parsing has made tremendous progress in the past 2 decades Magerman 1994 Ratnaparkhi 1997 Collins 1997 Charniak 2000 Klein and Manning 2003 Carreras et al. 2008 and accurate syntactic parsing is often assumed when developing other natural language applications. On the other hand there are plenty of language applications where basic syntactic information is insufficient. For instance in question answering it is highly desirable to have the semantic information of a syntactic constituent . a noun-phrase NP is a person or an organization an adverbial phrase is locative or temporal. As syntactic information has been widely used in machine translation systems Yamada and Knight 2001 Xiong et al. 2010 Shen et al. 2008 Chiang 2010 Shen et al. 2010 an interesting question is to predict whether or not a syntactic constituent is projectable1 across a language pair 1A constituent in the source language is projectable if it can be aligned to a contiguous span in the target language. 1230 Such problems can be abstracted as adding additional annotations to an existing tree structure. For example the English Penn treebank Marcus et al. 1993 contains function tags and many carry semantic information. To add semantic information to the basic syntactic trees a logical step .