RDF Graph Entailment

Question

I just read about the concept of entailment for RDF (Resource Description Framework).Can anyone tell me an example of entailment for two RDF graphs and explain them a bit.

Answer 1

Suppose you have the following :

ex:book1 rdf:type ex:Publication . 
ex:book2 rdf:type ex:Article .

So a Sparql query like SELECT ?s { ?s rdf:type ex:Publication } will return only ex:book1

If you add the fact (or a graph in your data set with the fact) that states :

ex:Article rdfs:subClassOf ex:Publication

If your sparql engine processes entailments, it should deduce that a ex:Article is also a ex:Publication

so SELECT ?s { ?s rdf:type ex:Publication } would return both ex:book1 AND ex:book2

PS: for more information, the example comes from http://www.w3.org/TR/2009/WD-sparql11-entailment-20091022/