Coordinate Structure Analysis with Global Structural Constraints and Alignment-Based Local Features

We propose a hybrid approach to coordinate structure analysis that combines a simple grammar to ensure consistent global structure of coordinations in a sentence, and features based on sequence alignment to capture local symmetry of conjuncts. The weight of the alignmentbased features, which in turn determines the score of coordinate structures, is optimized by perceptron training on a given corpus. A bottom-up chart parsing algorithm efficiently finds the best scoring structure, taking both nested or nonoverlapping flat coordinations into account. We demonstrate that our approach outperforms existing parsers in coordination scope detection on the Genia corpus.

• Type: Journal
• Year: 2009
• Where: ACL
• Authors: Kazuo Hara, Masashi Shimbo, Hideharu Okuma, Yuji Matsumoto
• Keywords: ACL 2009, Computational Linguistics, Consistent Global Structure, Coordination Scope Detection, Flat Coordinations