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	SUPPORT TOOLS FOR THE QUONTO SYSTEM Master Thesis in Computer Sciences Engineering University “Sapienza” of Rome, September 2007 by Manuel Dioturni Hosting enterprise: Epistematica Srl Relator: Prof. M.Lenzerini Tutor: Ing. M. Iacovella

One of the main research strands on Description Logics (DLs) concerns the compromise between the logic expressive power and the reasoning computability; these two aspects are directly proportional, so the best ratio has to be found: many DLs with effective reasoning algorithms (of P class, at worst) have not sufficient expressive power to represent conceptual models and basic ontology languages; by the other side, many DLs with sufficient expressive power lack in terms of reasoning capabilities (of EXPTIME class, at worst).

The QuOnto (Querying Ontologies) System has been developed to solve these problems: this Java-based, freeware (for non commercial uses) reasoner is the first automatic reasoner able to answer complex queries (union of conjunctive queries) posed over ontologies. QuOnto requires DL-Lite formalism and manage up to millions of instances, keeping logarithmic (LOGSPACE) complexity of query answering with respect to data size. However, QuOnto hasn’t a graphical user interface nor administrative tools, but requires user to know a specific XML syntax to define ontologies for reasoning submission; these interaction barriers result in poor dissemination of such reasoner.

For these reasons, this thesis work focused on the possibility to link QuOnto to some other system, as Protégé, known to be user-friendly and widespread through the Semantic Web community.

Protégé is a free and open-source ontology editor and allows to import/export ontologies with several formats (OWL, RDF Schema, XML Schema, etc. ). A large community of people uses Protégé and contributes to its updating; finally, its Java plug-in based architecture makes it easy to be extended.

The two above cited systems use different formalisms, thus a translation from Protégé language constructions (OWL) to QuOnto Description Logic assertions (DL-LiteF) has been performed. The project developing phase consisted mainly in the software implementation and testing, associated with detailed documentation and shared with the Protégé community.

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Image: Free reinterpretation of Quonto's and Protègè's logos