Certain Answers for SPARQL?

The standard semantics of SPARQL and the standard semantics of RDF differ fundamentally, sometimes leading to unintuitive answers. In this paper, we thus motivate an alternative semantics for SPARQL based on certain answers, taking into account the existential nature of blank nodes, the open-world assumption of RDF, and perhaps even the lack of a unique name assumption. We propose that SPARQL is a natural use-case for applying existing techniques that approximate certain answers in relational database settings.