Knowledge Graphs

A graph is a network of nodes and edges

In a knowledge graph, the edges are directed

One node-edge-node relationship is called a "triple" and describes a "statement" or a "fact"

A triple consists of a Subject, a predicate and an Object

An example from a BIM model

As more facts are added, the object in one triple becomes the subject in another

Objects can also represent simple datatype properties

ABox and TBox

The graph includes both the data and the schemas that describe this data

We distinguish between the assertion layer (ABox) and the terminology layer (TBox)

Querying the graph

Querying the graph is as easy as decribing a path along its edges

SPARQL: SPARQL Protocol and RDF Query Language

Advanced

With RDF* (RDF star) it is posible to make a statement about another statement

Let's imagine we would like to describe some provenance about this fact

In RDF* it would look like this

In Turtle* syntax it would look like this