Stemming and n-grams in Spanish: an evaluation of their impact on information retrieval

Abstract

At some stage, most of the models and techniques implemented in IR use frequency counts of the terms appearing in documents and in queries. However, many words, since they are derived from the same stem, have very close semantic contents. This makes a grouping of such variants under a single term advisable. Otherwise, dispersal occurs in the calculation of frequency of these terms, and it also becomes difficult to compare queries and documents. On the other hand, there are notable differences between different languages in the way of forming derivatives and inflected forms, so that the application of specific techniques can produce unequal results according to the language of the documents and queries. A description is given of the tests carried out for documents in Spanish, which involved some stemming techniques widely used in English, as well as the application of n-grams, and the results are compared.