Is a morphologically complex language really that complex in full-text retrieval

Abstract. In this paper we show that keyword variation of a morphologically complex language, Finnish, can be handled effectively for IR purposes by generating only the textually most frequent forms of the keyword. Theoretically Finnish nouns have about 2,000 different forms, but occurrences of most of the forms are rare. Corpus statistics showed that about 84 – 88 per cent of the occurrences of inflected noun forms are forms of only six cases out of the 14 possible. This number – maximally 2*6 – of keyword’s variant forms makes it feasible to try them all in a search. IR results of the frequen