  This paper presents a language-independent approach to controlled vocabulary
keyword assignment using the EUROVOC thesaurus. Due to the multilingual nature
of EUROVOC, the keywords for a document written in one language can be
displayed in all eleven official European Union languages. The mapping of
documents written in different languages to the same multilingual thesaurus
furthermore allows cross-language document comparison. The assignment of the
controlled vocabulary thesaurus descriptors is achieved by applying a
statistical method that uses a collection of manually indexed documents to
identify, for each thesaurus descriptor, a large number of lemmas that are
statistically associated to the descriptor. These associated words are then
used during the assignment procedure to identify a ranked list of those EUROVOC
terms that are most likely to be good keywords for a given document. The paper
also describes the challenges of this task and discusses the achieved results
of the fully functional prototype.
