CLEF 2006: ad hoc track overview

We describe the objectives and organization of the CLEF 2006 ad hoc track and discuss the main characteristics of the tasks offered to test monolingual, bilingual, and multilingual textual document retrieval systems. The track was divided into two streams. The main stream offered mono- and bilingual tasks using the same collections as CLEF 2005: Bulgarian, English, French, Hungarian and Portuguese. The second stream, designed for more experienced participants, offered the so-called