Building a large annotated corpus of English: the penn treebank
Computational Linguistics - Special issue on using large corpora: II
A parsing: fast exact Viterbi parse selection
NAACL '03 Proceedings of the 2003 Conference of the North American Chapter of the Association for Computational Linguistics on Human Language Technology - Volume 1
Learning accurate, compact, and interpretable tree annotation
ACL-44 Proceedings of the 21st International Conference on Computational Linguistics and the 44th annual meeting of the Association for Computational Linguistics
Hierarchical search for parsing
NAACL '09 Proceedings of Human Language Technologies: The 2009 Annual Conference of the North American Chapter of the Association for Computational Linguistics
The generalized A* architecture
Journal of Artificial Intelligence Research
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Hierarchical A* (HA*) uses of a hierarchy of coarse grammars to speed up parsing without sacrificing optimality. HA* prioritizes search in refined grammars using Viterbi outside costs computed in coarser grammars. We present Bridge Hierarchical A* (BHA*), a modified Hierarchial A* algorithm which computes a novel outside cost called a bridge outside cost. These bridge costs mix finer outside scores with coarser inside scores, and thus constitute tighter heuristics than entirely coarse scores. We show that BHA* substantially outperforms HA* when the hierarchy contains only very coarse grammars, while achieving comparable performance on more refined hierarchies.