C-structures and f-structures for the British National Corpus

Joachim Wagner (1) , Djamé Seddah (2) , Jennifer Foster (1) , Josef van Genabith (1)

1 NCLT - National Centre for Language Technology
2 LaLIC - Langues, logiques, informatiques, cognition

We describe how the British National Corpus (BNC), a one hundred million word balanced corpus of British English, was parsed into Lexical Functional Grammar (LFG) c-structures and f-structures, using a treebank-based parsing architecture. The parsing architecture uses a state-of-the-art statistical parser and reranker trained on the Penn Treebank to produce context-free phrase structure trees, and an annotation algorithm to automatically annotate these trees into LFG f-structures. We describe the pre-processing steps which were taken to accommodate the differences between the Penn Treebank and the BNC. Some of the issues encountered in applying the parsing architecture on such a large scale are discussed. The process of annotating a gold standard set of 1,000 parse trees is described. We present evaluation results obtained by evaluating the c-structures produced by the statistical parser against the c-structure gold standard. We also present the results obtained by evaluating the f-structures produced by the annotation algorithm against an automatically constructed f-structure gold standard. The c-structures achieve an f-score of 83.7% and the f-structures an f-score of 91.2%.

Mots clés: parsing; Probabilistic parsing; out of domain parsing; BNC

Domaines: Traitement du texte et du document

Joachim Wagner, Djamé Seddah, Jennifer Foster, Josef van Genabith. C-structures and f-structures for the British National Corpus. Proceedings of the Twelfth International Lexical Functional Grammar Conference, 2007, Stanford, CA, United States. ⟨inria-00545440⟩