Paper: Three-Dimensional Parametrization for Parsing Morphologically Rich Languages

ACL ID W07-2219
Title Three-Dimensional Parametrization for Parsing Morphologically Rich Languages
Venue Conference on Parsing Technologies
Session Main Conference
Year 2007
Authors

Current parameters of accurate unlexical- ized parsers based on Probabilistic Context- Free Grammars (PCFGs) form a two- dimensional grid in which rewrite events are conditioned on both horizontal (head- outward) and vertical (parental) histories. In Semitic languages, where arguments may move around rather freely and phrase- structures are often shallow, there are ad- ditional morphological factors that govern the generation process. Here we pro- pose that agreement features percolated up the parse-tree form a third dimension of parametrization that is orthogonal to the pre- vious two. This dimension differs from mere “state-splits” as it applies to a whole set of categories rather than to individual ones and encodes linguistically motivated co-occurrences between them. This paper pre...