Abstract

Error-driven pruning of treebank grammars for base noun phrase identification. Claire Cardie and David Pierce. In Proceedings of the 36th Annual Meeting of the Association for Computational Linguistics and COLING-98, pages 218-224, 1998. Available as cmp-lg/9808015.

Finding simple, non-recursive, base noun phrases is an important subtask for many natural language processing applications. While previous empirical methods for base NP identification have been rather complex, this paper instead proposes a very simple algorithm that is tailored to the relative simplicity of the task. In particular, we present a corpus-based approach for finding base NPs by matching part-of-speech tag sequences. The training phase of the algorithm is based on two successful techniques: first the base NP grammar is read from a ``treebank'' corpus; then the grammar is improved by selecting rules with high ``benefit'' scores. Using this simple algorithm with a naive heuristic for matching rules, we achieve surprising accuracy in an evaluation on the Penn Treebank Wall Street Journal.