Monolingual and Bilingual Experiments in GeoCLEF2006

This paper presents the results of our initial experiments in the monolingual English, Spanish and Portuguese tasks and the Bilingual Spanish → English, Spanish → Portuguese, English → Spanish and Portuguese → Spanish tasks. Twenty runs were submitted as official runs, thirteen for the monolingual task and seven for the bilingual task. We used the Terrier Information Retrieval Platform to run experiments for both tasks using the Inverse Document Frequency model with Laplace after-effect and normalization 2. Experiments included topics processed automatically as well as topics processed manually. Manual processing of topics was carried out using gazetteers (Alexandria Digital Library, European Parliament and GEOnet Names Server), some of them containing translations in languages other than English, others containing the latitude, longitude and area which allow for semi-automated spatial analysis (proximity analysis). For the bilingual task we developed a component based on the transfer approach in machine translation. Topics were pre-processed automatically to eliminate stopwords. Then topics in the source language were translated to the target language. A major problem we detected after submitting our results was that we did not include the Spanish newspaper collection for the year 95 (EFE 95) for indexing and retrieval purposes. Therefore, the results of our experiments with Spanish for the monolingual and bilingual tasks were affected in terms of recall and precision. We are currently rerunning experiments with the full Spanish collection for the monolingual and bilingual task to obtain a more accurate evaluation of the retrieval performance.