We used the grammar together with one of its pre-packaged conditional Maximum Entropy models for parse ranking, trained on a combination of encyclopedia articles and tourism brochures.
a semantically empty word is determined to be in-scope if there is an in-scope syntax tree node in the right position relative to it, as governed by a short list of templates organized by the type of the semantically empty word (particles, complementizers, non-referential pronouns, relative pronouns, and auxiliary verbs).