module ext_releasing_and_confining
  depends on releasing_and_confining

  function declarations
    fluents 
      basic
        shut_out_of : tangible_entity * tangible_entity -> booleans
        is_closed : spatial_entity -> booleans
        contained_in : tangible_entity * tangible_entity -> booleans

  axioms
    impossible occurs(X) if instance(X, confine),
                            object(X, O),
                            site(X, L),
                            shut_out_of(O, L).

    impossible occurs(X) if instance(X, confine),
                            site(X, L),
                            is_closed(L).

    impossible occurs(X) if instance(X, confine),
                            object(X, O),
                            site(X, L),
                            -contained_in(O, L).