Paper: Hard Constraints for Grammatical Function Labelling

ACL ID P10-1111
Title Hard Constraints for Grammatical Function Labelling
Venue Annual Meeting of the Association of Computational Linguistics
Session Main Conference
Year 2010

For languages with (semi-) free word or- der (such as German), labelling gramma- tical functions on top of phrase-structural constituent analyses is crucial for making them interpretable. Unfortunately, most statistical classifiers consider only local information for function labelling and fail to capture important restrictions on the distribution of core argument functions such as subject, object etc., namely that there is at most one subject (etc.) per clause. We augment a statistical classifier with an integer linear program imposing hard linguistic constraints on the solution space output by the classifier, capturing global distributional restrictions. We show that this improves labelling quality, in par- ticular for argument grammatical func- tions, in an intrinsic evaluation, and, im...