Creating a multilingual collocations dictionary from large text corpora

Creating a Multilingual Collocation Dictionary from Large Text Corpora Luka Nerima, Violeta Seretan, Eric Wehrli Language Technology Laboratory (LATL), Dept. of Linguistics University of Geneva CH-1211 Geneva 4, Switzerland fLuka.Nerima, Violeta.Seretan, Eric.Wehrlil@lettres.unige.ch Abstract This paper describes a system of termino- logical extraction capable of handling multi-word expressions, using a powerful syntactic parser. The system includes a concordancing tool enabling the user to display the context of the collocation, i.e. the sentence or the whole document where the collocation occurs. Since the corpora are multilingual, the system also offers an alignment mechanism for the correspond- ing translated documents. 1 Introduction Cross-linguistic communication frequently raises the problem of the proper understanding of idio- matic expressions, i.e. multi-word expressions whose meaning differs from the composition of the individual meaning of their parts. The importance of multi-word expressions is widely recognized in the domains of translation and terminology. These expressions can usually not be translated literally, and one must find adequate correspondences in the target language. This paper describes a system of terminological extraction capable of handling multi-word expres- sions, based on a detailed linguistic analysis. The originality of our approach comes from the fact that collocations are not extracted from raw texts, but rather from syntactically parsed texts. The lin- guistic analysis selects potential pairs of words, as only the words occurring in a specific syntactic configuration will be taken into account for further statistical processing. Such a chain of processes significantly increases the quality and the rele- vance of the extracted collocations. This system will be applied to textual corpora from the World Trade Organisation (WTO), which consist in parallel documents in three languages: English, French and Spanish. All the examples given in this paper are taken from these corpora. Ultimately, the system will enrich the workbench of translators and terminologists of this organiza- tion. 2 Collocations The notion of "collocation" is difficult to define in a very precise way. Commonly used to refer to an arbitrary and recurrent word combination (Be n- son, 1990), it is also often taken as a conventional combination of two or more words, with a more or less transparent meaning. "Conventional combina- tions" means that native speakers recognize such combinations as the "correct" way of expressing a particular concept. For instance, substituting one term of a collocation with a synonym or a near- synonym is usually felt by native-speakers as being "not quite right", although perfectly understand- able, e.g. firing ambition vs. burning ambition or in French exercer une profession vs. pratiquer une profession (to practice a profession). For further discussion on collocations, see (Gross 1996; Man- ning and Schiitze, 1999; Wehrli, 2000). In spite of the lack of agreement over what ex- actly counts as collocation, computational linguists agree that collocations and more generally multi- word expressions play a very important role in many NLP applications such as terminology ex- traction, translation, information retrieval, and multilingual text alignment. This, along with the ever-increasing availability of very large text cor- 131 pora, has triggered an important …

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