如何从Java中owl类的“Equivalent To”部分中定义的类表达式中检索对象属性？

Question

I have defined (in Protege) a class Missing which is equivalent to ((not (atHome value 30)) and (not (atWork value 30)))and (not (onleave value 30)). By using OWL-API, I would like to obtain the single object properties (in this case, the negated object properties) from the class expression , in order to further get their domains and ranges and perform further reasoning. However, I am not sure how to parse the whole equivalent class expression in Java.

For now I am able to retrieve the equivalent class expression of a class (in this case Missing) in functional form with the following code.

localOntology.getEquivalentClassesAxioms(missingClass);

The provided code returns the functional representation of the equivalence class expression I have provided in Protege, however I am not able to parse it and retrive not (atWork value 30), not (atHome value 30), not (onleave value 30), which is what I would like.

Answer 1

• First. In the described above ontology IRIs atHome , atWork and onleave are not object properties, but rather data properties, since atHome value 30 is a Literal Value Restriction , that has datatype property, not object property. If, of course, it is not Punning .

• In OWL-API v5, the method OWLOntology#getEquivalentClassesAxioms(OWLClass) is deprecated. Instead it is recommended to use its Java-Stream-API companion: OWLOntology#equivalentClassesAxioms(OWLClass)

• Using this method the solution (getting all data properties for the specified OWL Class) might look like this:

  o.equivalentClassesAxioms(c) .flatMap(OWLNaryClassAxiom::operands) .filter(x -> x instanceof OWLObjectComplementOf) .map(x -> ((OWLObjectComplementOf) x).getOperand()) .filter(x -> x instanceof OWLDataHasValue) .flatMap(x -> ((OWLDataHasValue) x).components()) .filter(x -> x instanceof OWLDataProperty) .forEach(System.out::println);

• the same can be rewritten using the standard Java Collections API, but more cumbersome.

• Also, it is possible to use org.semanticweb.owlapi.util.OWLObjectComponentCollector or org.semanticweb.owlapi.util.OWLEntityCollector utility tools, but theses particular impls collect all components in a single Set , so it is still need to filter the result:

  o.equivalentClassesAxioms(c) .flatMap(a -> new OWLObjectComponentCollector().getComponents(a) .stream().filter(x -> x instanceof OWLDataProperty)) .forEach(System.out::println) ;

• create your own org.semanticweb.owlapi.util.AbstractCollectorEx impl to collect only data properties.