E.A. Fox et al. (Eds.): ICADL 2005, LNCS 3815, pp. 38 – 43, 2005. © Springer-Verlag Berlin Heidelberg 2005 An Ontology-Based Model of Digital Libraries László Kovács and András Micsik MTA SZTAKI, Computer and Automation Research Institute, of the Hungarian Academy of Sciences, Department of Distributed Systems, H-1111 Budapest XI. Lágymányosi u. 11. Hungary {laszlo.kovacs, micsik}@sztaki.hu Abstract. In this paper a new unifying model is suggested for digital libraries which contains four conceptual layers, and defines the concepts of each layer as an OWL ontology. Instances of the ontology can be used to define an overall view of a digital library in terms of the four layers and the relationships be- tween them. Such a model has the advantage that the methodology is formal- ized and extensible, thus models are comparable and manageable. Keywords: digital library concepts, ontologies, reference models, OWL. 1 Introduction Digital libraries represent a truly interdisciplinary research domain; modeling activi- ties in this area thus have very complex requirements. Models related to digital librar- ies published so far can be grouped as follows: • External models have some overlap with the digital library research area, but these models are widely used outside the area as well [3,4], • Partial models are restricted to certain views or services of digital libraries [5,6,7,9]. Models for digital library evaluation form a subset of partial models, for example [2,10], • Generalized models: the 5S model [8] is a formal model for digital libraries, while the DELOS model can be seen as a conceptual model [1]. The single general model applicable for digital libraries is the 5S model [8]. Ac- cording to this model a digital library consists of a repository, metadata catalogs, ser- vices and a society of users. The 5S refers to streams and structures for the construc- tion of digital objects, spaces for the description of digital object collections and their interrelations, scenarios for the definition of how services and activities change the state of the system, and finally societies for the interconnection of roles and activities within the user community. The 5S model is based on mathematical formalism, and has been used in various case studies, including the generation of a taxonomy of DL terms. 5SL is a declarative language based on this model for the generation of DL applications. Another holistic view of digital library is given by the DELOS working group for digital library testbeds and evaluation [1]. Although the model focuses on evaluation,