Archive for the ‘Reification’ Category

Foundations of an Alternative Approach to Reification in RDF

Tuesday, June 17th, 2014

Foundations of an Alternative Approach to Reification in RDF by Olaf Hartig and Bryan Thompson.


This document defines extensions of the RDF data model and of the SPARQL query language that capture an alternative approach to represent statement-level metadata. While this alternative approach is backwards compatible with RDF reification as defined by the RDF standard, the approach aims to address usability and data management shortcomings of RDF reification. One of the great advantages of the proposed approach is that it clarifies a means to (i) understand sparse matrices, the property graph model, hypergraphs, and other data structures with an emphasis on link attributes, (ii) map such data onto RDF, and (iii) query such data using SPARQL. Further, the proposal greatly expands both the freedom that database designers enjoy when creating physical indexing schemes and query plans for graph data annotated with link attributes and the interoperability of those database solutions.

The essence of the approach is to embed triples “in” triples that make statements about the embedded triples.

Works more efficiently than the standard RDF alternative but that’s hardly surprising.

Of course, you remain bound to lexical “sameness” as the identification for the embedded triple but I suppose fixing that would not be backwards compatible with the RDF standard.

I recommend this if you are working with RDF data. No point in it being any more inefficient than absolutely necessary.

PS: Reification is one of those terms that should be stricken from the CS vocabulary.

The question is: Can you make a statement about X? If the answer is no, there is no “reification” of X. Your information system cannot speak of X, which includes assigning any properties to X.

If the answer is yes, then the question is how do you identify X? Olaf and Bryan answer by saying “put a copy of X right here.” That’s one solution.

I first saw this in a tweet by Marin Dimitrov.