    
    private String showRelation(TypeOf_Relation r)
    {
        String predicate          = r.predicate          ;

        String relation = "{" 
        + serializeParticipant(r.subject.size(), r.subject.listIterator())
        + " → " + predicate 
        + " → " 
        + serializeParticipant(r.object.size(), r.object.listIterator())
        + "}" ;

        return relation ; 
    	
    }   //  end of method showRelation()



    private String serializeParticipant(int arraySize, 
                                        ListIterator<TypeOf_Relation.RelationMemberData> itr)
    {
        String participants = "" ;
        int numofSubjects   = 0 ;

        while (itr.hasNext())
        {
            TypeOf_Relation.RelationMemberData x = itr.next() ;

            String class_name = x.OWLclassName      ; 
            
            if (++numofSubjects < arraySize)
                participants  += (class_name + ", ") ;
            else
                participants  += class_name ;
        }

        return participants ;
        
    }   //  end of method serializeParticipant()

