Wide-coverage efficient statistical parsing with CCG and log-linear models

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Wide-coverage efficient statistical parsing with CCG and log-linear models (2007)

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by Stephen Clark , James R. Curran

Venue:	COMPUTATIONAL LINGUISTICS
Citations:	216 - 43 self

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@ARTICLE{Clark07wide-coverageefficient,
    author = {Stephen Clark and James R. Curran},
    title = {Wide-coverage efficient statistical parsing with CCG and log-linear models},
    journal = {COMPUTATIONAL LINGUISTICS},
    year = {2007},
    volume = {33}
}

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Abstract

This paper describes a number of log-linear parsing models for an automatically extracted lexicalized grammar. The models are "full" parsing models in the sense that probabilities are defined for complete parses, rather than for independent events derived by decomposing the parse tree. Discriminative training is used to estimate the models, which requires incorrect parses for each sentence in the training data as well as the correct parse. The lexicalized grammar formalism used is Combinatory Categorial Grammar (CCG), and the grammar is automatically extracted from CCGbank, a CCG version of the Penn Treebank. The combination of discriminative training and an automatically extracted grammar leads to a significant memory requirement (over 20 GB), which is satisfied using a parallel implementation of the BFGS optimisation algorithm running on a Beowulf cluster. Dynamic programming over a packed chart, in combination with the parallel implementation, allows us to solve one of the largest-scale estimation problems in the statistical parsing literature in under three hours. A key component of the parsing system, for both training and testing, is a Maximum Entropy supertagger which assigns CCG lexical categories to words in a sentence. The supertagger makes the discriminative training feasible, and also leads to a highly efficient parser. Surprisingly,

Keyphrases

discriminative training wide-coverage efficient statistical parsing log-linear model parallel implementation correct parse bfgs optimisation algorithm maximum entropy supertagger complete par parse tree statistical parsing literature beowulf cluster independent event log-linear parsing model parsing system penn treebank combinatory categorial grammar packed chart significant memory requirement lexicalized grammar largest-scale estimation problem ccg version efficient parser dynamic programming extracted grammar training data lexicalized grammar formalism incorrect par ccg lexical category key component

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