Ontologies have established themselves as a powerful tool to enable knowledge sharing, and a growing number of applications have benefited from the use of ontologies as a means to achieve semantic interoperability among heterogeneous, distributed systems [1]. With the evolution of cooperative and distributed systems, and the emergence of the semantic Web, ontologies have become an indispensable resource. The number of ontologies available on the Web has also increased due to the appearance of several tools that assist users in creating their ontologies. This has posed problems of understanding and reuse of those resources already difficult to design. A solution was then proposed by the knowledge engineers namely modularization. Ontology modularization is crucial to support knowledge reuse on the ever increasing semantic Web [2]. However, modularization methods that serve the reuse goal are often intended for humans to assist them in building new ontologies, rather than for applications that need only a relevant part of an existing ontology. Moreover, modules obtained are always subject to verification and maintenance by humans to validate the semantic consistency of their contents. Unlike previous studies, we investigate in this paper how a modularization based on semantic comparison, may provide a module directly reusable by the application that requests it. Our contribution is twofold. On the one hand, it allows an application to extract and use a module that covers a subdomain from an ontology that covers a wider knowledge area, regardless of its structure and the formalism with which it is expressed. On the other hand, the user is relieved from manually estimating the meaning of the components of the ontology, after the modularization process.
The modularization approach we propose is part of the decomposition approaches
of monolithic ontologies [
For example, in an ontology that describes the human anatomy, the user is only interested in the anatomy of the foot. The method should extract a coherent module, semantically rich on the foot, from the ontology of departure.
Our approach is based on two basic steps: ─ 1st step: Identifying concepts that are in strong semantic relationship with external concepts. ─ 2nd step: composition of the module based on the concepts identified in Step 1. All concepts that appear in the definition of the concepts identified are considered part of the module.
The goal is to allow a program to extract automatically a single part of an ontology without human intervention and without restrictions on the ontology structure. This will help programs to satisfy their requirements by reusing directly ontology portions.