y ?System)
        )
    )
  (:action alert
       :parameters ( ?System - system ?Guard - guard)
       :precondition (and 
            (emergency ?System)
            (working ?Guard ?System)
       )
       :effect (and 
            (not (working ?Guard ?System))
            (alerted ?Guard ?System)
        )
    )
  (:action back_to_work
       :parameters ( ?Guard - guard ?System - system)
       :precondition 
            (alerted ?Guard ?System)
       :effect (and 
            (not (alerted ?Guard ?