Automatically extracting and representing collocations for language generation

Collocational knowledge is necessary for language generation. The problem is that collocations come in a large variety of forms. They can involve two, three or more words, these words can be of different syntactic categories and they can be involved in more or less rigid ways. This leads to two main difficulties: collocational knowledge has to be acquired and it must be represented flexibly so that it can be used for language generation. We address both problems in this paper, focusing on the acquisition problem. We describe a program, Xtract, that automatically acquires a range of collocations from large textual corpora and we describe how they can be represented in a flexible lexicon using a unification based formalism.