Paper: Smoothing fine-grained PCFG lexicons

ACL ID W09-3833
Title Smoothing fine-grained PCFG lexicons
Venue International Conference on Parsing Technologies
Session Main Conference
Year 2009

We present an approach for smoothing treebank-PCFG lexicons by interpolating treebank lexical parameter estimates with estimates obtained from unannotated data via the Inside-outside algorithm. The PCFG has complex lexical categories, making relative-frequency estimates from a treebank very sparse. This kind of smoothing for complex lexical categories results in improved parsing performance, with a particular advantage in identify- ing obligatory arguments subcategorized by verbs unseen in the treebank.