AAAI Publications, Twelfth International Conference on the Principles of Knowledge Representation and Reasoning

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Query and Predicate Emptiness in Description Logics
Franz Baader, Meghyn Bienvenu, Carsten Lutz, Frank Wolter

Last modified: 2012-03-03


Ontologies can be used to provide an enriched vocabulary for the formulation of queries over instance data. We identify query emptiness and predicate emptiness as two central reasoning services in this context. Query emptiness asks whether a given query has an empty answer over all data sets formulated in a given signature. Predicate emptiness is defined analogously, but quantifies universally over all queries that contain a given predicate. In this paper, we determine the computational complexity of query emptiness and predicate emptiness in the EL, DL-Lite, and ALC-families of description logics, investigate the connection to ontology modules, and perform a practical case study to evaluate the new reasoning services.


description logic; query answering; emptiness; complexity

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