We extend the description logic EL++ with reflexive roles
and range restrictions, and show that subsumption remains tractable if
a certain syntactic restriction is adopted. We also show that subsumption
becomes PSpace-hard (resp. undecidable) if this restriction is weakened
(resp. dropped). Additionally, we prove that tractability is lost when
symmetric roles are added: in this case, subsumption becomes ExpTime-
hard
What is the Semantic Web? Read on for a brief introduction to the Semantic Web, how to get started using it, and to understand why we should invest in making our content semantic.
Ontotext GraphDB is a highly-efficient and robust graph database with RDF and SPARQL support. This documentation is a comprehensive guide, which explains every feature of GraphDB as well as topics such as setting up a repository, loading and working with data, tuning its performance, scaling, etc.
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