module interpretation
  depends on entity_event_and_action

  sort declarations
    interpret :: actions
    learn :: interpret

    intangible_entity :: entity
    conceptual_entity :: intangible_entity
    message :: conceptual_entity
    information :: conceptual_entity

  function declarations
    fluents
      basic
        is_known : entity -> booleans
        known_to : entity * tangible_entity -> booleans        

  axioms
    known_to(X, Y) if is_known(X).
    -known_to(X, Y) if -is_known(X).

    false if instance(X, interpret),
             -defined_agent(X).

    false if instance(X, interpret),
             agent(X, A),
             -instance(A, tangible_entity).

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

    false if instance(X, interpret),
             object(X, O),
             -instance(O, message).  

    result(X) = R if instance(X, interpret),
                     object(X, O),
                     result(X1, O),
                     object(X1, R),
                     instance(R, information).

    occurs(X) causes known_to(O, A) if instance(X, interpret),
                                       object(X, O),
                                       agent(X, A).