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Head-Driven Phrase Structure Grammar Parsing on Penn Treebank

2019-07-05ACL 2019Code Available0· sign in to hype

Junru Zhou, Hai Zhao

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Abstract

Head-driven phrase structure grammar (HPSG) enjoys a uniform formalism representing rich contextual syntactic and even semantic meanings. This paper makes the first attempt to formulate a simplified HPSG by integrating constituent and dependency formal representations into head-driven phrase structure. Then two parsing algorithms are respectively proposed for two converted tree representations, division span and joint span. As HPSG encodes both constituent and dependency structure information, the proposed HPSG parsers may be regarded as a sort of joint decoder for both types of structures and thus are evaluated in terms of extracted or converted constituent and dependency parsing trees. Our parser achieves new state-of-the-art performance for both parsing tasks on Penn Treebank (PTB) and Chinese Penn Treebank, verifying the effectiveness of joint learning constituent and dependency structures. In details, we report 96.33 F1 of constituent parsing and 97.20\% UAS of dependency parsing on PTB.

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Benchmark Results

DatasetModelMetricClaimedVerifiedStatus
CTB5Zhou etal. 2019F1 score89.4Unverified
Penn TreebankHead-Driven Phrase Structure Grammar Parsing (Joint) + XLNetF1 score96.33Unverified
Penn TreebankHead-Driven Phrase Structure Grammar Parsing (Joint) + BERTF1 score95.84Unverified

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