Semantic Web Search Based on Ontological Conjunctive Queries

Thomas Lukasiewicz, Bettina Fazzinga, Giorgio Gianforme, Georg Gottlob


Abstract: Many experts predict that the next huge step forward in Web information technology will be
achieved by adding semantics to Web data, and will possibly consist of (some form of) the Semantic
Web. In this paper, we present a novel approach to Semantic Web search, which allows for a semantic
processing of Web search queries, and for evaluating complex Web search queries that involve
reasoning over the Web. More specifically, we first add ontological structure and semantics to Web
pages, which then allows for both attaching a meaning to Web search queries and Web pages, and for
formulating and processing ontology-based complex Web search queries (that is, conjunctive queries)
that involve reasoning over the Web. Here, we assume the existence of an underlying ontology (in a
lightweight ontology language) relative to which Web pages are annotated and Web search queries are
formulated. Depending on whether we use a general or a specialized ontology, we thus obtain a general
or a vertical Semantic Web search interface, respectively. That is, we are actually mapping the Web into
an ontological knowledge base, which then allows for Semantic Web search relative to the underlying
ontology. The latter is then realized by reduction to standard Web search on standard Web pages and
logically completed ontological annotations. That is, standard Web search engines are used as the main
inference motor for ontology-based Semantic Web search. We develop the formal model behind this
approach and also provide an implementation in desktop search. Furthermore, we report on extensive
experiments, including a implemented Semantic Web search on the Internet Movie Database.

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Type of Paper: Research Paper
Keywords: Semantic Web search; description logics; conjunctive queries; ontology reasoning; paradigms for semantic search; scalable algorithms and infrastructures for semantic search
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