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.
|N||,||N/N||N||(S[adj]\ NP)\ NP|
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|