Text Reduction-Enrichment at WebCLEF

In this paper we are reporting the results obtained after submitting one run to the Mixed Monolingual task of WebCLEF 2006. We have used a text reduction process based on the selection of mid-frequency terms. Although our approach enhances precision, it must be improved in recall by an enrichment process based on the addition of high co-ocurrence terms. We have seen that a improvement of 40% in the corpus used last year in the BiEnEs was obtained. But we also observed that low Mean Reciprocal Rank (MRR) values were obtained compared with those of the mixed monolingual task of WebCLEF 2005. We consider that our low MRR is derived of a bad preprocessing phase, but we must investigate this issue in detail.