Document
  (
  Prefix(ex http://example.org/example#)
  Prefix(xs http://www.w3.org/2001/XMLSchema#)
  
Group 
  (
  Forall ?Name 
    (
    ex:customer[
        ex:discount -> "10"^^xs:integer
        ex:name -> ?Name] 
    :- 
      ex:customer[
        ex:status -> "gold"
        ex:name -> ?Name]
    )
    
  Forall ?Name 
    (
      ex:customer[
        ex:discount -> "5"^^xs:integer
        ex:name -> ?Name]
      :-
      ex:customer[
        ex:status -> "silver"
        ex:name -> ?Name]
    )
    
  )
)