let display_one fmt v =
    State_set.iter (fun value ->
                 if not (Relations_type.Model.is_reachable value) then begin
                   Format.fprintf fmt "Statement (x%d): UNREACHABLE@\n"
                     v.counter_unroll ;
                 end
                 else
                   (Format.fprintf fmt "Statement (x%d)@\n%a"
                      v.counter_unroll
                      Relations_type.Model.pretty
                      value))
      !(v.value)