@prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#>.
@prefix owl: <http://www.w3.org/2002/07/owl#>.
@prefix swrl: <http://www.w3.org/2003/11/swrl#>.
@prefix : <foo://bla#>.
:john :hasChild :bob; :hasSibling :paul, [].
:hasSibling a owl:SymmetricProperty.
:paul a [a owl:Restriction; owl:onProperty :hasChild; owl:minCardinality 1].

:uncleRule a swrl:Imp;
   swrl:head ([ a swrl:IndividualPropertyAtom; swrl:propertyPredicate :uncle1;
                 swrl:argument1 :y ; swrl:argument2 :z ]);
   swrl:body ([ a swrl:IndividualPropertyAtom; swrl:propertyPredicate :hasChild;
                 swrl:argument1 :x ; swrl:argument2 :y ]
              [ a swrl:IndividualPropertyAtom; swrl:propertyPredicate :hasSibling;
                 swrl:argument1 :x ; swrl:argument2 :z ]).
   :x a swrl:Variable.    :y a swrl:Variable.   :z a swrl:Variable.
[ owl:propertyChain ([owl:inverseOf :hasChild] :hasSibling) ] rdfs:subPropertyOf :uncle2.
:Uncle owl:equivalentClass [a owl:Restriction; owl:onProperty :hasSibling;
  owl:someValuesFrom [a owl:Restriction; owl:onProperty :hasChild;
                      owl:minCardinality 1]].