Ora Lassila, Amazon Web Services, Principal Technologist
Adrian Gschwend, QLeverize, Zazuko, CEO

In the RDF specification, reification is probably the most disliked but also the most misunderstood feature. There has been a long-running discussion in the RDF community about how to “fix” reification. The feature itself is important, because it allows one to make “statements about statements”, and this not only enables use cases like provenance, but can also be seen as a way to move RDF and Labeled Property Graphs (LPGs) closer to one another (provided we are able to “fix” the mechanism and make it easily usable). The W3C RDF-star Working Group is nearing the completion of RDF version 1.2, and this set of specifications will introduce a lightweight and more usable mechanism for reification, in turn making it easy to use “edge properties” or even “edges between edges”.

In this presentation we will give an overview of the long road that has led to the new standard, and will explain the mechanism in detail. The new feature introduces changes to RDF syntax and semantics, but the Working Group has been extremely careful in maintaining backward compatibility, ensuring that existing RDF applications will not be disrupted. We will explain how the addition to RDF syntax works, and will explain the extended semantics. We will also discuss potential future work, such as extensions to RDF-Schema (to enable ontologies to be defined that make use of the new feature) as well as the recent interest from the LPG community to find a technical approach for RDF/LPG compatibility.