incorrect inferrence of bottom class

[tobiaswjohn]

I am using Openllet to compute inferred axioms and I discovered an incorrect inference. Here is a minimal example.

• Ontology in functional syntax:

Prefix(:=<http://www.example.org/reasonerTester#>)
Prefix(owl:=<http://www.w3.org/2002/07/owl#>)

Ontology (

    Declaration(Class(:C))
    Declaration(NamedIndividual(:a))

    Declaration(ObjectProperty(:r))
    Declaration(ObjectProperty(:s))

    EquivalentClasses(
        ObjectIntersectionOf(
            ObjectHasSelf(:s) 
            :C
        ) 
        ObjectSomeValuesFrom(
            :r 
            owl:Thing
        ) 
    )

    ReflexiveObjectProperty( :s)
)

• The problem:
  Openllet infers the axiom EquivalentClasses(C owl:Nothing), which (to the best of my knowledge) should not be inferred from the ontology. (I also cross-checked with HermiT, which does not infer the axiom).

• For reproduction, here is the call from my program using OWL API:

OWLOntologyDocumentSource source = new FileDocumentSource(ontFile, new FunctionalSyntaxDocumentFormat());
OWLOntologyManager manager = OWLManager.createOWLOntologyManager();
ont = manager.loadOntologyFromOntologyDocument(source);
OWLReasoner openllet = OpenlletReasonerFactory.getInstance().createReasoner(ont);

List<InferredAxiomGenerator<? extends OWLAxiom>> gens = new ArrayList<>();
gens.add( new InferredEquivalentClassAxiomGenerator());

InferredOntologyGenerator iog = new InferredOntologyGenerator(openllet, gens);
OWLOntology infOnt = manager.createOntology();
iog.fillOntology(ont.getOWLOntologyManager().getOWLDataFactory(), infOnt);