Allow parsing of OWL qualified cardinality restrictions even when the onProperty is not known to be an Object or Datatype property.

[chrispetsos]

I use OWL API version 4 and the following snippet,

manager = OWLManager.createOWLOntologyManager();  
        try {  
            ontology = manager.loadOntologyFromOntologyDocument(new StreamDocumentSource(axioms));  
        } catch (OWLOntologyCreationException e) {  
            e.printStackTrace();  
        }

to load the following ontology that contains a qualified cardinality restriction,

@prefix : <http://www.seerc.org/test/pellet-icv#> .
@prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#> .
@prefix xsd: <http://www.w3.org/2001/XMLSchema#>.
@prefix owl: <http://www.w3.org/2002/07/owl#> .

:Manager rdfs:subClassOf
              [ a owl:Restriction ;
                owl:onProperty :manages ;
                owl:qualifiedCardinality "1"^^xsd:nonNegativeInteger ;
                owl:onClass :Department
              ] .

The OWL API logs the following,

0 [main] ERROR org.semanticweb.owlapi.rdf.rdfxml.parser.OWLRDFConsumer - Entity not properly recognized, missing triples in input? http://org.semanticweb.owlapi/error#Error1 for type Class

The ontology contains the Error1 class,

SubClassOf(http://www.seerc.org/test/pellet-icv#Manager http://org.semanticweb.owlapi/error#Error1) AnnotationAssertion(owl:qualifiedCardinality _:genid1 "1"^^xsd:nonNegativeInteger)

and the cardinality restriction is not parsed correctly.
When i declare :manages as Object Property,

@prefix : <http://www.seerc.org/test/pellet-icv#> .
@prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#> .
@prefix xsd: <http://www.w3.org/2001/XMLSchema#>.
@prefix owl: <http://www.w3.org/2002/07/owl#> .

:Manager rdfs:subClassOf
              [ a owl:Restriction ;
                owl:onProperty :manages ;
                owl:qualifiedCardinality "1"^^xsd:nonNegativeInteger ;
                owl:onClass :Department
              ] .

:manages a owl:ObjectProperty .

it parses the ontology correctly,

Declaration(ObjectProperty(http://www.seerc.org/test/pellet-icv#manages)) SubClassOf(http://www.seerc.org/test/pellet-icv#Manager ObjectExactCardinality(1 http://www.seerc.org/test/pellet-icv#manages http://www.seerc.org/test/pellet-icv#Department))

No Error1 class and the cardinality restriction is parsed correctly.

My suggestion is that whenever a property is not known to be an Object or Datatype property, to default to an Object Property if we are in LAX mode. What do you think about such an enhancement? Any good strategies to tackle such a requirement? Would a solution be to alter a bit the logic here?

[ignazio1977]

Can you describe what you wish to happen?

When a property is undefined, parser behavior is supposed to be to throw exceptions.

In order to deal with real world data, we attempt to treat such cases with a best guess, but we need more information on this one.

[ignazio1977]

Sorry, saw your update after my comment

[chrispetsos]

The new title represents what my original intention was after all... i'll issue a new pull request that tries to fulfill this in a more elegant way.