Paper: A SNoW Based Supertagger With Application To NP Chunking

ACL ID P03-1064
Title A SNoW Based Supertagger With Application To NP Chunking
Venue Annual Meeting of the Association of Computational Linguistics
Session Main Conference
Year 2003

Supertagging is the tagging process of assigning the correct elementary tree of LTAG, or the correct supertag, to each word of an input sentence1. In this pa- per we propose to use supertags to expose syntactic dependencies which are unavail- able with POS tags. We first propose a novel method of applying Sparse Network of Winnow (SNoW) to sequential models. Then we use it to construct a supertagger that uses long distance syntactical depen- dencies, and the supertagger achieves an accuracy of a2a4a3a6a5a8a7a10a9a12a11. We apply the su- pertagger to NP chunking. The use of su- pertags in NP chunking gives rise to al- most a9a12a11 absolute increase (from a2a4a3a6a5a14a13a16a15a16a11 to a2a4a3a6a5a17a2a4a18a16a11 ) in F-score under Transforma- tion Based Learning(TBL) frame. The surpertagge...