@prefix rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>.
@prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#>.
@prefix owl: <http://www.w3.org/2002/07/owl#>.
@prefix : <foo://bla/names#>.

[ a owl:ObjectPropertyAssertion;
  rdf:subject :x;
  rdf:predicate :higher;
  rdf:object :y].
#owl:NegativeObjectPropertyAssertion(:a :higher :a).