Towards Structural Criteria for Ontology Modularization

Recently, the benefits of modular representations of ontologies has been recognized by the semantic web community. Existing methods for splitting up models into modules either optimize for completeness of local or for the efficiency of distributed reasoning. In our work on semantics-based P2P systems, we are also concerned with the additional criteria of robustness or reasoning in cases where peers are unavailable and with ease of maintenance. We define a number of structural criteria for modularized ontologies and argue why these criteria are suitable for estimating efficiency, robustness and maintainability. We apply the criteria to a number of modularization approaches and discuss the trade-offs made. Based on the discussion we propose a general quality measure for modular representations in the context of our use case.