What grammars tell us about corpora : the case of reduced relative clausesPaola

We present a large (65 million words of Wall Street Journal) and in-depth corpus study of a particular syntactic ambiguity to investigate (1) to what extent the structure of a grammar is reeected in a corpus, and (2) how probability functions deened according to a grammar t independently established measures of syntactic disambiguation preference. We look at the well-known case of the ambiguity between a main clause and reduced relative construction. We measure the probability distributions of several linguistic features (transitiv-ity, tense, voice) over a sample of optionally intransitive verbs. In agreement with recent results on parsing with lexicalised probabilistic grammars (Collins, 1997; Srinivas, 1997), we nd that statistics over lexical, as opposed to structural, features best correspond to human intuitive judgments and to experimental nd-ings. These results are enlightening to investigate novel uses of corpora, by assessing the portability of statistics across tasks, and by determining what is needed for useful syntactic annotation of corpora.