Efficiently Answering Queries to DL and Rules Web Ontologies

Tools required in the Semantic Web include ontology reasoning and Web source query-answering services which are provided by inference engines. Large Web ontologies have been created for complex domains, and source ontologies (annotations) are heterogeneous and distributed across different Web locations. Integrated Web source query processing entails a query reformulation phase where reasoning on the domain ontologies will need to be done; user queries must be rewritten in terms of the Web sources and must be evaluated against the Web source ontologies. For an expressive and decidable ontology language specified as a combination of DL and Rules Languages, this research considers optimization techniques and evaluation strategies that will be developed and tested for both the query reformulation and the query answering phase. We will combine cost-based and heuristic-based optimization techniques with evaluation strategies that determine which portion of an ontology is required. We will adopt one of the existing formalisms for combining DL languages and Datalog: DL-SafeRules, and a Web ontology language, XWebSOGO, will be specified in this formalism. The current XWebSOGO-S Datalog system will be extended, and we will conduct experimental studies to examine the quality of the implemented

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