  Both the notion of Property Graphs (PG) and the Resource Description
Framework (RDF) are commonly used models for representing graph-shaped data.
While there exist some system-specific solutions to convert data from one model
to the other, these solutions are not entirely compatible with one another and
none of them appears to be based on a formal foundation. In fact, for the PG
model, there does not even exist a commonly agreed-upon formal definition.
  The aim of this document is to reconcile both models formally. To this end,
the document proposes a formalization of the PG model and introduces
well-defined transformations between PGs and RDF. As a result, the document
provides a basis for the following two innovations: On one hand, by
implementing the RDF-to-PG transformations defined in this document, PG-based
systems can enable their users to load RDF data and make it accessible in a
compatible, system-independent manner using, e.g., the graph traversal language
Gremlin or the declarative graph query language Cypher. On the other hand, the
PG-to-RDF transformation in this document enables RDF data management systems
to support compatible, system-independent queries over the content of Property
Graphs by using the standard RDF query language SPARQL. Additionally, this
document represents a foundation for systematic research on relationships
between the two models and between their query languages.
