Designing Ontology-Based Interactive Information Retrieval Interfaces Elena Garc´ıa 1 and Miguel- ´ Angel Sicilia 2 1 Computer Science Department, Alcal´a University, Ctra. Barcelona km. 33600 – 28871 Alcal´a de Henares (Madrid), Spain elena.garciab@uah.es 2 Computer Science Department, Carlos III University, Av. Universidad, 30 – 28911 Legan´es (Madrid), Spain msicilia@inf.uc3m.es Abstract. The so-called Semantic Web advocates the future availabil- ity of machine-understandable metadata, describing Web resources by means of ontologies expressed in description logics. This would eventually entail changes in Information Retrieval (IR) indexing and matching algo- rithms, but also in the user interface design of IR tools. This second as- pect can be informed by existing Interactive Information Retrieval (IIR) research, but it requires also further investigations about the interaction of users with terminological structures and iterative, browsing-oriented query construction paradigms. In this paper, preliminary experiences and reflections regarding ontology-based query formulation interface design are described. 1 Introduction Information Retrieval (IR) can be defined as a discipline concerned with the formulation and resolution of queries issued by users against a database of in- formation items (possibly heterogeneous in format and structure). According to [3], the effective retrieval of relevant information is affected both by the user task and the logical view of the information items. The interaction of the user with the IR system usually comprises both retrieval and browsing activities, oriented toward fulfilling an information need. The logical representation of an item is a representation of its contents, in many cases consisting on a set of keywords ex- tracted by humans or by means of automated mechanisms. Both elements have been extensively studied in the last decades from two complementary perspec- tives: a system approach and an interaction approach. The system approach is mainly concerned with the process of matching a query against the database of items, in an attempt to produce optimal rankings. The interaction approach — often referred to as Interactive Information Retrieval (IIR) — puts emphasis in human factors, stressing the iterative nature of information searching (a review can be found in [20]), and extending the scope of IR to the needs, motivations and strategies of users in their interaction with IR systems.