CCG supertagging

Combinatory Categorical Grammar (CCG; Steedman, 2000) is a highly lexicalized formalism. The standard parsing model of Clark and Curran (2007) uses over 400 lexical categories (or supertags), compared to about 50 part-of-speech tags for typical parsers.

Example:

Vinken	,	61	years	old
N	,	N/N	N	(S[adj]\ NP)\ NP

CCGBank

The CCGBank is a corpus of CCG derivations and dependency structures extracted from the Penn Treebank by Hockenmaier and Steedman (2007). Sections 2-21 are used for training, section 00 for development, and section 23 as in-domain test set. Performance is only calculated on the 425 most frequent labels. Models are evaluated based on accuracy.

Model	Accuracy	Paper / Source
Lewis et al. (2016)	94.7	LSTM CCG Parsing
Vaswani et al. (2016)	94.24	Supertagging with LSTMs
Low supervision (Søgaard and Goldberg, 2016)	93.26	Deep multi-task learning with low level tasks supervised at lower layers
Xu et al. (2015)	93.00	CCG Supertagging with a Recurrent Neural Network

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