Supertagging with combinatory categorial grammar for dependency parsing

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2014

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Akkuş, Burak Kerim

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Combinatory Categorial Grammar (CCG) categories contain syntactic and semantic information. CCG derivation trees can be used in extracting partial dependency structures by providing the missing information in order to build complete dependency structures. Therefore, CCG categories are sometimes referred to as supertags. The amount of information encoded in supertags makes it possible to create very accurate and fast parsers as supertagging is considered ``almost parsing''. In this thesis, a maximum entropy based part of speech tagger is presented to improve the performance of CCG supertagging and another maximum entropy classifier is implemented with additional features for supertagging. Morphological features of words of an agglutinative language such as Turkish are used in order to improve the accuracy of POS tagging and supertagging processes. This indicates direct relationships between morphemes and lexical categories. The effects of using the improved supertagger are tested on dependency parsers by means of using supertags as rich parts of speech tags. Additionally, using POS taggers that assign multiple part of speech tags to the ambiguous words is suggested as another potential improvement for supertaggers.

Subject Keywords

Entropy (Information theory)., Combinatory logic., Categorial grammar., Parsing (Computer grammar).

URI

http://etd.lib.metu.edu.tr/upload/12617970/index.pdf
https://hdl.handle.net/11511/24059

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Graduate School of Natural and Applied Sciences, Thesis

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Citation Formats

B. K. Akkuş, “Supertagging with combinatory categorial grammar for dependency parsing,” M.S. - Master of Science, Middle East Technical University, 2014.