OWLClass a = df.getOWLClass(IRI.create("urn:A"));
OWLClass b = df.getOWLClass(IRI.create("urn:B"));
OWLClass c = df.getOWLClass(IRI.create("urn:C"));
OWLClass d = df.getOWLClass(IRI.create("urn:D"));
OWLAxiom ax = df.getOWLDisjointClassesAxiom(a, b, c, d);
DLSyntaxObjectRenderer visitor = new DLSyntaxObjectRenderer();
String render = visitor.render(ax);
assertEquals("A ⊑ ¬ B, A ⊑ ¬ C, A ⊑ ¬ D, B ⊑ ¬ C, B ⊑ ¬ D, C ⊑ ¬ D",
render);
}