Title: Hierarchical A* Parsing with Bridge Outside Scores
Abstract: 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.
Publication Year: 2010
Publication Date: 2010-07-11
Language: en
Type: article
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Cited By Count: 6
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