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xmlrdfowlswi-prologprotege

How to query an individual for its object property from an OWL RDF/XML using SWI-Prolog?

I specified an "isPartOf" object property in Protege, and I asserted that

"Room_1 isPartOf Apartment_1".

Both "Room_1" and "Apartment_1" are individuals. The relevant codes in the OWL file are like the following:

<rdf:RDF xmlns="http://www.xxx.come/example#"
 xml:base="http://www.xxx.come/example"
 xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
 xmlns:owl="http://www.w3.org/2002/07/owl#"
 xmlns:xml="http://www.w3.org/XML/1998/namespace"
 xmlns:xsd="http://www.w3.org/2001/XMLSchema#"
 xmlns:rdfs="http://www.w3.org/2000/01/rdf-schema#">


<!-- http://www.xxx.come/example#isPartOf -->

<owl:ObjectProperty rdf:about="http://www.xxx.come/example#isTemporalPartOf">
    <rdf:type rdf:resource="http://www.w3.org/2002/07/owl#AsymmetricProperty"/>
    <rdf:type rdf:resource="http://www.w3.org/2002/07/owl#TransitiveProperty"/>
    <rdf:type rdf:resource="http://www.w3.org/2002/07/owl#ReflexiveProperty"/>
    <rdfs:domain rdf:resource="http://www.xxx.come/example#Room"/>
    <rdfs:range rdf:resource="http://www.xxx.come/example#Apartment"/>
</owl:ObjectProperty>


<!-- http://www.xxx.come/example#Room_1 -->

<owl:NamedIndividual rdf:about="http://www.xxx.come/example#Room_1">
    <rdf:type rdf:resource="http://www.xxx.come/example#Room"/>
    <isPartOf rdf:resource="http://http://www.xxx.come/example#Apartment_1"/>
    <hasSize rdf:datatype="http://www.w3.org/2001/XMLSchema#double">99.6</hasSize>
    <hasSize rdf:datatype="http://www.w3.org/2001/XMLSchema#double">145.5</hasSize>
</owl:NamedIndividual>
</rdf:RDF>

How would you query such a triple using Prolog? I thought it would be something like:

is_part_of(Ind1, Ind2):- 
    rdf(Ind1, 
        "http://www.w3.org/1999/02/22-rdf-syntax-ns#isPartOf, 
        Ind2).

which apparently doesn't work.

I also saw rdf_has(S,P,O,RealP) from rdf library that looks kindof usable, but the specification is vague.

Following this question, what if the two individuals are classes? What if the object property is a datatype property instead?

I think I'm stuck on an easy problem, but I've searched a long time for an example or similar question but didn't find anything.

Thanks in advance!

Solution

  • Probably the problem is the absence of a quick start example in the semweb/rdf_db documentation. Here is an example session.

    
?- use_module(library(semweb/rdf_db)).
true.

?- rdf_load('example.owl', [format(xml)]).
% Parsed "example.owl" in 0.01 sec; 11 triples
true.

?- rdf(Ind1, 'http://www.xxx.come/example#isPartOf',  Ind2).
Ind1 = 'http://www.xxx.come/example#Room_1',
Ind2 = 'http://http://www.xxx.come/example#Apartment_1'.

?- rdf(Ind1, 'http://www.xxx.come/example#hasSize',  Ind2).
Ind1 = 'http://www.xxx.come/example#Room_1',
Ind2 = literal(type('http://www.w3.org/2001/XMLSchema#double', '99.6')) .

?- % is_part_of(Ind1, Ind2):- rdf(Ind1, 'http://www.xxx.come/example#isPartOf', Ind2).
|    ['rules.pl'].
true.

?- is_part_of(Ind1, Ind2).
Ind1 = 'http://www.xxx.come/example#Room_1',
Ind2 = 'http://http://www.xxx.come/example#Apartment_1'.

?- rdf_register_prefix(ex, 'http://www.xxx.come/example#').
true.

?- rdf(Ind1, ex:isPartOf,  Ind2).
Ind1 = 'http://www.xxx.come/example#Room_1',
Ind2 = 'http://http://www.xxx.come/example#Apartment_1'.

    Errors in your code:

    1. Atoms in Prolog should be enclosed within single quotes.
      As for double quotes — see e.g this question. My SWI-Prolog says:

      Type error: `atom' expected, found `"http://www.xxx.come/example#isPartOf"' (a string)

      Anyway, double quotes should be closed, too.

    2. You should use correct full URIs: http://www.xxx.come/example#isPartOf instead of http://www.w3.org/1999/02/22-rdf-syntax-ns#isPartOf.

    3. This malformed URI — http://http://www.xxx.come/example#Apartment_1 — may cause additional problems.