RDF vs Graphs
Typically people think of RDF as graph. But it is actually a subject of research on how to represent RDF as formal graph.
I will show examples of RDFs and how they would be represented as formal graph if we do naive “transformation”.
See: A Comparative Study on Representing RDF as Graph and Hypergraph Data Model.
# Directed graph
RDF


Graph
Not quite what we want  we can’t distinguish that there is no connection between :a
and :d
.
# Directed labeled graph
RDF


Graph
Not quite what we want  we can’t use label as start (or end) of an edge.
# Bipartite graph
See: Bipartite Graphs as Intermediate Model for RDFstar, Inductive Triple Graphs: A purely functional approach to represent RDF
RDF


Graph
Some observations:
 it is bipartite graph
 but also directed labeled graph with only three labels:
s
 subjectp
 predicateo
 object
 It is also visually reminds standard RDF reification
 but it looks nothing like what original RDF “graph”
# Directed hypergraph
See: Directed hypergraphs for RDF documents
To be precise it is 3unifor Fhypergraph with additionally defined function(s), which tells which node is subject, object and tail (on the graph I use edge labels to denote this, but this is for visual purposes only, this is no labeled graph)
RDF:


Graph:
as bipartite graph
# The Labeled Directed Multigraph with Triple Nodes (LDM3N)
See: A Formal Graph Model for RDF and Its Implementation
RDF:


RDF triple is splitted into two labeled edges  they get same unique suffix and one of two suffixes: I
stands for initial, T
stands for terminal.