Using Thesauri for Automatic Indexing and for the Visualisation of Multilingual Document Collections

This article presents an approach for cross-language document comparison and for the visualisation of multilingual document collections. Document comparison usually relies on the calculation of the degree of lexical overlap between documents. As this is not possible for documents written in different languages, the contents of these documents first have to be mapped onto a language-independent representation. The JRC’s statistical tool for controlled vocabulary keyword assignment assigns descriptors of the multilingual Eurovoc thesaurus, which can be used for cross-language document comparison. The language-independent sets of thesaurus descriptors allow to identify, for a given document, the most similar documents even if they are written in different languages. They furthermore allow to organise and to visualise the structure and approximate contents of whole multilingual document collections in two-dimensional document maps.