Check out the new blog post Problems of the RDF syntax:

An RDF syntax (notation) is a concrete syntax for writing (serializing) RDF triples. There are many different notations, some of which are based on existing formats (XML, (X)HTML, JSON), while others use special formats (Turtle).

The problems of the RDF model, discussed in the previous posts, are inherited by RDF notations. Various special cases require special support in a syntax, which makes it more complex. However, RDF notations contain a number of their own problems, which can be divided into two categories:

  • various problems in RDF notations
  • the lack of a single dominant notation
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Check out the new blog post The Ultimate Problem of RDF and the Semantic Web on

In the previous posts I’ve covered two important problems of the RDF model, related to blank nodes and literals. Here, I’m going to focus on what I think is the key problem of RDF – the problem of the node of an RDF graph.

In the RDF: Concepts and Abstract Syntax, a node is defined as follows:

“The set of nodes of an RDF graph is the set of subjects and objects of triples in the graph.”

It then states that a node can be a URI reference, a literal or a blank node. However, the concept of a node itself is not clearly defined. What is it that is common to all different types of nodes? What requirements does a node need to meet in order to be a node?

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