Turning a Dependency Treebank into a PSG-style Constituent Treebank

Eckhard Bick


Abstract
In this paper, we present and evaluate a new method to convert Constraint Grammar (CG) parses of running text into Constituent Treebanks. The conversion is two-step - first a grammar-based method is used to bridge the gap between raw CG annotation and full dependency structure, then phrase structure bracketing and non-terminal nodes are introduced by clustering sister dependents, effectively building one syntactic treebank on top of another. The method is compared with another approach (Bick 2003-2), where constituent structures are arrived at by employing a function-tag based Phrase Structure Grammar (PSG). Results are evaluated on a small reference corpus for both raw and revised CG input, with bracketing F-Scores of 87.5% for raw text and 97.1% for revised CG input, and a raw text edge label accuracy of 95.9% for forms and 86% for functions, or 99.7% and 99.4%, respectively, for revised CG. By applying the tools to the CG-only part of the Danish Arboretum treebank we were able to increase the size of the treebank by 86%, from 197.400 to 367.500 words.
Anthology ID:
L06-1269
Volume:
Proceedings of the Fifth International Conference on Language Resources and Evaluation (LREC’06)
Month:
May
Year:
2006
Address:
Genoa, Italy
Venue:
LREC
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Publisher:
European Language Resources Association (ELRA)
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Language:
URL:
http://www.lrec-conf.org/proceedings/lrec2006/pdf/452_pdf.pdf
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Cite (ACL):
Eckhard Bick. 2006. Turning a Dependency Treebank into a PSG-style Constituent Treebank. In Proceedings of the Fifth International Conference on Language Resources and Evaluation (LREC’06), Genoa, Italy. European Language Resources Association (ELRA).
Cite (Informal):
Turning a Dependency Treebank into a PSG-style Constituent Treebank (Bick, LREC 2006)
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PDF:
http://www.lrec-conf.org/proceedings/lrec2006/pdf/452_pdf.pdf