module impairment
  depends on entity_event_and_action

  sort declarations
    impair :: actions
    repair :: actions

  function declarations
    fluents
      basic
        is_broken : entity -> booleans
        is_ruined : entity -> booleans

  axioms
    is_broken(X) if is_ruined(X).

    -is_ruined(X) if -is_broken(X).

    false if instance(X, impair),
             -defined_object(X).

    false if instance(X, impair),
             object(X, O),
             -instance(O, tangible_entity).


    false if instance(X, repair),
             -defined_object(X).

    false if instance(X, repair),
             object(X, O),
             -instance(O, tangible_entity).
    
    occurs(X) causes -is_broken(O) if instance(X, repair),
                                     object(X, O).

    impossible occurs(X) if instance(X, repair),
                            object(X, O),
                            -is_broken(O).

    impossible occurs(X) if instance(X, repair),
                            object(X, O),
                            is_ruined(O).