Tassos Venetis

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Query rewriting over lightweight ontologies, like DL-Lite ontologies, is a prominent approach for ontology-based data access. It is often the case in realistic scenarios that users ask an initial query which they later refine, e.g., by extending it with new constraints making their initial request more precise. So far, all DL-Lite systems would need to(More)
Interoperability is a strong requirement in open distributed systems and in the Semantic Web. The need for ontology integration is not always completely met by the available ontology matching techniques because, in most cases, the semantics of the compared ontologies is not considered, thus leading to inconsistent mappings. Probabilistic approaches has been(More)
— The Semantic Web can be viewed as largely about " Knowledge meets the Web ". Thus its vision includes ontologies and rules. A key requirement for the architecture of the Semantic Web is to be able to layer " rules on top of ontologies " and " ontologies on top of rules ". This has as a counterpart the definition of a mapping between Description Logics and(More)
Fuzzy extensions to Description Logics (DLs) have gained considerable attention the last decade. So far most works on fuzzy DLs have focused on either very expressive languages, like fuzzy OWL and OWL 2, or on highly inexpressive ones, like fuzzy OWL 2 QL and fuzzy OWL 2 EL. To the best of our knowledge a fuzzy extension to the language OWL 2 RL has not(More)
Ontologies expressed in Description Logics or extensions of Datalog are gradually used for describing the domain of many research and industrial strength applications. They provide a formal semantically rich and data-independent layer over which user queries can be posed. A prominent technique for query answering in ontology-based applications is query(More)
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