The Limitations of the Single-Relational Graph
• A single-relational graph is only able to express a single type of vertex
(e.g. person, city, user, webpage).1
• A single-relational graph is only able to express a single type of edge
(e.g. collaborator, road, follows, citation).2
• For modelers, these are very limiting graph types.
This is not completely true. All n-partite single-relational graphs allow for the division of the vertex set
into n subsets, where V = n Ai : Ai ∩ Aj = ∅. Thus, its possible to implicitly type the vertices.
This is not completely true. There exists an injective, information-preserving function that maps any
multi-relational graph to a single-relational graph, where edge types are denoted by topological structures.
Rodriguez, M.A., “Mapping Semantic Networks to Undirected Networks,” International Journal of Applied
Mathematics and Computer Sciences, 5(1), pp. 39–42, 2009. [http://arxiv.org/abs/0804.0277]