A study on the use of stemming for monolingual ad-hoc portuguese information retrieval

Abstract

For UFRGS's first participation in CLEF our goal was to compare the performance of heavier and lighter stemming strategies using the Portuguese data collections for monolingual Ad-hoc retrieval. The results show that the safest strategy was to use the lighter alternative (reducing plural forms only). On a query-by-query analysis, full stemming achieved the highest improvement but also the biggest decrease in performance when compared to no stemming. In addition, statistical tests showed that the only significant improvement in terms of mean average precision, precision at ten and number of relevant retrieved was achieved by our lighter stemmer. © Springer-Verlag Berlin Heidelberg 2007.