RDF-star and SPARQL-star are basically Property Graph interfaces if you don't validate with e.g. RDFS (schema.org,), SHACL, json-ld-schema (jsonschema+shacl), and/or OWL.

Justify Linked Data; https://5stardata.info/

W3C RDF-star and SPARQL-star > 2.2 RDF-star Graph Examples: https://w3c.github.io/rdf-star/cg-spec/editors_draft.html#rd...

    def to_matrices(g: rdflib.MultiDiGraph) -> Union[Matrix, Tensor]

rdflib.MultiDiGraph: https://networkx.org/documentation/stable/reference/classes/...

Multigraph: https://en.wikipedia.org/wiki/Multigraph :

> In mathematics, and more specifically in graph theory, a multigraph is a graph which is permitted to have multiple edges (also called parallel edges[1]), that is, edges that have the same end nodes. Thus two vertices may be connected by more than one edge ... [which requires multidimensional matrices, netcdf (pydata/xarray,), tensors, or a better implementation of a representation; and edge reification in RDF]

From "Why tensors? A beginner's perspective" https://news.ycombinator.com/item?id=30629931 :

> https://en.wikipedia.org/wiki/Tensor

... Tensor product of graphs: https://en.wikipedia.org/wiki/Tensor_product_of_graphs

Hilbert space: https://en.wikipedia.org/wiki/Hilbert_space :

> The inner product between two state vectors is a complex number known as a probability amplitude.