Exploiting named entity classes in CCG surface realization

Abstract

This paper describes how named entity (NE) classes can be used to improve broad coverage surface realization with the OpenCCG realizer. Our experiments indicate that collapsing certain multi-word NEs and interpolating a language model where NEs are replaced by their class labels yields the largest quality increase, with 4-grams adding a small additional boost. Substantial further benefit is obtained by including class information in the hypertagging (supertagging for realization) component of the system, yielding a state-of-the-art BLEU score of 0.8173 on Section 23 of the CCGbank. A targeted manual evaluation confirms that the BLEU score increase corresponds to a significant rise in fluency.