Paper: Three Dependency-and-Boundary Models for Grammar Induction

ACL ID D12-1063
Title Three Dependency-and-Boundary Models for Grammar Induction
Venue Conference on Empirical Methods in Natural Language Processing
Session Main Conference
Year 2012

We present a new family of models for unsu- pervised parsing, Dependency and Boundary models, that use cues at constituent bound- aries to inform head-outward dependency tree generation. We build on three intuitions that are explicit in phrase-structure grammars but only implicit in standard dependency formu- lations: (i) Distributions of words that oc- cur at sentence boundaries ? such as English determiners ? resemble constituent edges. (ii) Punctuation at sentence boundaries fur- ther helps distinguish full sentences from fragments like headlines and titles, allow- ing us to model grammatical differences be- tween complete and incomplete sentences. (iii) Sentence-internal punctuation boundaries help with longer-distance dependencies, since punctuation correlates with constituent edges. ...