What's needed to make this inference?

问题:

If I want to infer that "Obama bornIn USA" from these facts:

 Obama bornIn Hawaii 
 Hawaii partOf USA

Are these two facts sufficient to make the inference? If yes, should RDFS or OWL be used to represent the facts? Is there some online SPARQL tool that I can quickly test those facts specification and inference based on the facts?

回答1:

Nobody knows what is bornIn or partOf. You should find an appropriate ontology or model this stuff yourself. There are several ways to do it.

OWL 2 capabilities

OWL 2 DL capabilities are sufficient to make the inference you want.
All you need is a property chain.

Here below a sample ontology serialized into the RDF Turtle format.

@prefix : <http://www.semanticweb.org/ontologies/ontology#> .
@prefix owl: <http://www.w3.org/2002/07/owl#> .
@prefix rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#> .

<http://www.semanticweb.org/ontologies/ontology> rdf:type owl:Ontology .

:Obama    rdf:type owl:NamedIndividual ; :bornIn :Honolulu .
:Honolulu rdf:type owl:NamedIndividual ; :partOf :Hawaii .
:Hawaii   rdf:type owl:NamedIndividual ; :partOf :USA .
:USA      rdf:type owl:NamedIndividual .

:bornIn rdf:type owl:ObjectProperty ; owl:propertyChainAxiom ( :bornIn :partOf ) .

:partOf rdf:type owl:ObjectProperty .

Common rule languages

You could replace the property chain axiom with the following SWRL rule.

bornIn(?person, ?place1) ^ partOf(?place1, ?place2) -> bornIn(?person, ?place2)

SWRL operates on ontological level. Other more or less common rule languages (e.g. SPIN) operate on RDF serialization level.

Triplestore-specific rule languages

In GraphDB, you could define a "ruleset" of this kind:

Prefices { obama: http://www.semanticweb.org/ontologies/ontology# }

Axioms { }

Rules
{
    Id: custom
      a <obama:bornIn> b
      b <obama:partOf> c
    -----------------------
      a <obama:bornIn> c
}

---

Is there some online SPARQL tool that I can quickly test those facts specification and inference based on the facts?

Questions asking to recommend or find a tool or other off-site resource are off-topic for SO. However, the table below compares some popular tools.

+---------+-----+------+-----+-------+
|         | OWL | SWRL |  …  | rules |
+---------+-----+------+-----+-------+
| Protege |  +  |  +   |  …  |   –   |
| Stardog |  +  |  +   |  …  |   +   |
| GraphDB |  ±  |  –   |  …  |   +   |
|    …    |  …  |  …   |  …  |   …   |
+---------+-----+------+-----+-------+

I'd suggest you try GraphDB Cloud. When creating a repository:

• load the ruleset above, if you want to use GraphDB's rule language, or
• select the built-in OWL-RL ruleset, if you want to use OWL 2 capabilities.