Representing and Querying Negative Knowledge in RDF

Typically, only positive data can be represented in RDF. However, negative knowledge representation is required in some application domains such as food allergies, software incompatibility and school absence. We present an approach to represent and query RDF data with negative data. We provide the syntax, semantics and an example. We argue that this approach fits into the open-world semantics of RDF according to the notion of certain answers.