Over the past few years, we have seen the emergence of large knowledge graphs combining information from multiple sources. Sometimes, this information is provided in the form of assertions about other assertions, defining contexts where assertions are valid. A recent extension to RDF which admits statements over statements, called RDF-star, is in revision to become a W3C standard. However, there is no proposal for a semantics of these RDF-star statements nor a built-in facility to operate over them. In this talk I will present our ongoing work proposing a query language for epistemic RDF-star metadata based on a four-valued logic. Our proposed query language, extends SPARQL-star, the query language for RDF-star, with a new type of FROM clause to facilitate operating with multiple and sometimes conflicting beliefs.
Daniel Hernandez is a postdoctoral researcher in the Analytic Computing department of the Institute for Artificial Intelligence at the University of Stuttgart. Previously, he was a postdoctoral researcher in the Computer Science Department at Aalborg University and worked at Millennium Institute Foundational Research on Data in Chile. He holds a Ph.D. in Computer Science from the University of Chile. His main interests include databases, the Semantic Web, data provenance and knowledge graphs.
